A Faster Algorithm for the Steiner Tree Problem

Aachen Department of Computer Science Technical Report

A Faster Algorithm for the Steiner Tree Problem

Daniel M¨olle, Stefan Richter, Peter Rossmanith

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ISSN 0935–3232 RWTH Aachen

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Aachener Informatik Berichte Department of Computer Science

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AIB-2005-04 ·

March 2005

The publications of the Department of Computer Science of RWTH Aachen University are accessible through the World Wide Web in general. http://aib.informatik.rwth-aachen.de/

A Faster Algorithm for the Steiner Tree Problem⋆ Daniel M¨ olle, Stefan Richter, Peter Rossmanith Lehr- und Forschungsgebiet Theoretische Informatik RWTH Aachen, Germany Email: {moelle,richter,rossmani}@cs.rwth-aachen.de

Abstract. The best algorithm for the Steiner tree problem by Dreyfus and Wagner is 33 years old. We celebrate this occasion and present a variation on this theme. A new `algorithm is developed, which improves the running time from ´ O(3k · n3 ) to O (2 + ε)k · poly(n) .

Dieses Baums Blatt, der von Osten Meinem Garten anvertraut, Gibt geheimen Sinn zu kosten, Wie’s den Wissenden erbaut. — J.W. v. Goethe

1

Prologue

It is commonly believed in the scientific community that NP-hard problems cannot be solved in polynomial time. Nevertheless, we have to deal with many of these in everyday applications. Earlier scholarship has addressed this dilemma in a number of ways, among them approximation, randomized algorithms, parameterized complexity, heuristics and many more. Recently, there has been renewed vigor in the field of exact algorithms, and the exponential run-time bounds for many problems have been improved. Some remarkable examples for such improvement have been achieved with new algorithms for 3-Satisfiability [4], Dominating Set [6] and Max-Cut [3]. The Steiner tree problem on networks is to find a subgraph of minimum total edge weight that connects all nodes in a given node subset. Since we assume positive weights for all edges, this subgraph must be a tree. The respective decision problem, in which we ask for the existence of such a subgraph whose weight does not exceed a given limit, is known to be NP-complete. The optimization problem is also APX-complete, even if the edge weights are restricted to {1, 2} [1]. On the positive side, it is approximable within 1 + (ln 3)/2, or within 1.28 in the aforementioned restricted variation [7]. The best exact algorithm for the Steiner tree problem known today is due to Dreyfus and Wagner [2]. Given a graph with n nodes, a set of k terminals and a function encoding the lengths of the edges, it computes a minimum Steiner tree in time O(3k n+2k n2 +n2 log n+nm) using dynamic programming. In this paper, we present an algorithm achieving the same in time O(ck ·poly(n)) for some c < 3. ⋆

Supported by the DFG under grant RO 927/6-1 (TAPI)

In fact, we can prove bounds of O(ck · poly(n)) for arbitrary 2 < c < 3, with large constants hidden in the Landau notation for small values of c. For a terminal set Y of size k, the Dreyfus-Wagner algorithm works as follows. It first computes optimal Steiner trees for all subsets of Y of size two, then it uses these results to compute optimal Steiner trees for all subsets of Y of size three, and so on, until an optimal Steiner tree for Y itself is found. The crucial lemma behind this algorithm introduces the Dreyfus-Wagner recursion (as it is called in [5]), giving a strategy to find an optimal Steiner tree for a given terminal set quickly by combining two optimal Steiner trees for two subsets with specific properties. One of the basic ideas used in the Dreyfus-Wagner recursion is the following: if T is an optimal Steiner tree for some terminal set Y ∪ {v} and v is not a leaf in T , we can split T at v to get optimal Steiner trees T1 and T2 for Y ′ ∪ {v} and (Y − Y ′ ) ∪ {v}, where Y ′ is the set of terminals in T1 . In this paper, we will extend this concept as follows: instead of splitting the tree at a single node v, we choose an entire set X of nodes to split the tree at, where |X| is bounded by 1/ε for an adjustable parameter ε. An important fact is that there exists such a set X for which each of the resulting subtrees contains at most ε|Y | + 1 of the terminals from Y . Using some additional ideas, this allows for a dynamic programming algorithm that successively combines locally optimal Steiner trees, constructing a globally optimal Steiner tree for the terminal set Y ∪ X. In the case that some optimal Steiner tree for Y contains all the nodes from X, the constructed tree is also an optimal Steiner tree for Y .

2

Chopping trees

As already stated in the introduction, our algorithm relies on the fact that there exists a set X of nodes to split the tree at such that the resulting subtrees contain no more than ε|Y | terminals each. This is formalized by the following lemma. Lemma 1. Let ε > 0, and let T be a tree with root r and k ≥ 1/ε2 terminals. Then there exists a set X of nodes such that 1. the subtree rooted at any child of any node x ∈ X ∪ {r} has at most εk terminals that are not part of any subtree rooted at a child of some successor x′ ∈ X − {x} of x, and 2. the size of X does not exceed ⌈1/ε⌉. Proof. The following algorithm computes a set X that fulfills the conditions described in the lemma: Let X := ∅. If T contains no more than εk terminals, output X, and stop. Otherwise, let v := r. For all the children c1 , . . . , cd of v, count the amount of terminals contained in the subtrees rooted at c1 , . . . , cd , and let m(v) be the maximum of these amounts. 5. If m(v) ≤ εk, add v to X, remove all the subtrees rooted at c1 , . . . , cd , and go to step 2.

1. 2. 3. 4.

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6. Otherwise, in the case that m(v) > εk, let v be one of the ci with a maximal amount of terminals in the respective subtree, and go to step 4. It is easy to see that the algorithm terminates on every input. Clearly, the output X satisfies the first condition of the lemma, as the algorithm only adds a node to X if the subtrees rooted at children of that node contain a sufficiently small amount of terminals that have not yet been processed. By cutting off processed subtrees, as done in step 5, the algorithm just avoids to count terminals that lie in subtrees of children of previously chosen nodes. To see that the second condition is fulfilled, note that the subtree rooted at the currently inspected node v (in steps 4 through 6) always contains more than εk unprocessed terminals: otherwise, a parent of v would have been chosen as a node to cut at. Hence, when v is added to X in step 5 and all the subtrees rooted at children of v are cut off, more than εk − 1 terminals disappear, where the term −1 is included because v can be one of the terminals itself. This processing of terminals continues while more than εk terminals remain. In total, and because ε ≥ ε/k, we get that         1−ε 1 1−ε 1 k − εk = = ≤ . |X| ≤ εk − 1 ε − 1/k ε 1 − 1/εk ε ⊓ ⊔ For an example, see Figure 1. Without loss of generality, we assume that henceforth 1/ε be an integer.

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Fig. 1. Example for Lemma 1 (k = 15, ε = 15 , εk = 3; |X| = 3 ≤ 5)

We intend to group nodes from X in so-called links, whenever they serve to delimit a subtree (together with some terminals). Definition 1. Let X be a set. A multiset X = {X1 , . . . , Xr } with X1 , . . . , Xr ∈ 2X \ {∅} is called a chain mail for X if |Xi ∩ Xj | ≤ 1 for any 1 ≤ i < j ≤ r and GX := ({1, . . . , r}, EX ), EX := { {i, j} | Xi 6= Xj ∧ Xi ∩ Xj 6= ∅ }, is a tree. The elements of a chain mail are called links. 5

Note that a chain mail is a special kind of multiset, in that two links Xi , Xj may be identical only if they are singletons. This makes sense in our context as can be seen from the way we create chain mails in Corollary 1. To build up the final tree T , we first want to look at subtrees Ti that span a link Xi and some subset Yi of the terminals. Na¨ıvely, we might be inclined to simply select the subtrees cut off in Lemma 1; unfortunately, there might be too many of these to try them all out, since multiple links in a chain mail are allowed to contain the same set of nodes from X. Thus, in the next lemma, we create bigger subtrees by unifying several links. Lemma 2. Let ε > 0, and let T be a rooted tree with k ≥ 1/ε2 terminals. Moreover, let X be the set given by the algorithm used in the proof of Lemma 1. The subtrees of T , as cut off by the algorithm, can be mapped to 3/ε containers such that all the subtrees in each container were cut off at the same node from X and contain together at most εk terminals. Proof. Let us extend the algorithm presented in the proof of Lemma 1. Whenever a node is chosen to be added to X, some amount s of subtrees with at most εk terminals gets cut off the remaining tree. Create s new containers, and map each subtree onto one of them. While there are two containers with no more than 12 εk terminals in their subtrees, unite them. When this loop terminates, at most one of the remaining containers has less than 21 εk terminals in its subtrees. In total, at most εk nodes are added to X, and hence, at most εk containers with less than 12 εk terminals in their subtrees remain. All other containers have more than 21 εk terminals, and because there are k terminals in T , there can be no more than k/( 21 εk) = 2/ε of them. Altogether, when our extended algorithm terminates, at most 3/ε containers remain. ⊓ ⊔ Definition 2. Let ε > 0, and let T be a tree with terminal set Y , |Y | ≥ 1/ε2 . A chain mail X is said to be a mirror of T if there are subsets Y1 ∪ . . . ∪ Yr = Y , such that there are optimal Steiner trees Ti for the terminal sets Xi ∪ Yi which combine to form the entire tree T . In this case we will also say that X breaks the terminal set into pieces Y1 ∪ . . . ∪ Yr = Y . We call this mirror q-granular if furthermore each subset Yi is of size at most q. Corollary 1. Let ε > 0, and let T be a tree with k ≥ 1/ε2 terminals. Then there is an (εk + 1)-granular mirror of T for a base set X with |X| ≤ 1/ε, and X contains at most 3/ε links. Proof. In the proof of Lemma 2, add to each container its respective cut node from X, and form new links as a union of old ones in the same way we formed containers from subtrees. It is easy to see that the resulting trees are optimal Steiner trees. ⊓ ⊔

3

Running in chain mail

The following two lemmata play an important rˆole for the runtime analysis of our algorithm. We estimate the number of relevant chain mails for a given set X as well as the number of steps required to compute optimal Steiner trees for some small terminal sets. 6

Lemma 3. Let X be a set of nodes and m := |X|. The number of chain mails 3m−1
2m−2 for X with 3m links is bounded by m m−1 .

Proof. Every chain mail induces a tree GX = ({X1 , . . . , Xr }, EX ) where EX = { {i, j} | Xi 6= Xj ∧ Xi ∩ Xj 6= ∅}. We first prove that there are no more than m inner nodes in GX . This bound is tight, as exemplified by the chain mail X = {{1}, {1, 2}, {2, 3}, . . . , {m − 1, m}, {m}} for X = {1, . . . , m}. Being a tree, GX can be constructed top-down, starting from an arbitrarily picked root. By definition of EX , we also have that every node Xi in GX other than the root shares exactly one element h(i) from X — imagine a hook on which the new link dangles — with its parent. It is easy to see that, at any step in the inductive construction of the tree GX , for any leaf Xi to be transformed into an inner node, a new leaf Xj with h(j) ∈ Xi \ {h(i)} must be added. Observe that h(j) cannot be used to turn any other leaf into an inner node later, because h(j) cannot occur in any previously attached link and will be a hook in any new link which contains this element. Now the claim follows from |X| ≤ m. In order to achieve a non-trivial bound on the number of chain mails, we distinguish two phases in the inductive construction of X and GX : adding the first m nodes, some or all of which can become inner nodes in the entire process of building the tree, and attaching 2m leaves. Again, we use both the notion of forming a chain mail and the notion of forming the respective tree. For the analysis of the first phase, we estimate as follows: Select a hook for each link safe the root, and then distribute the remaining nodes from X. There are m −1 links to select hooks from X for, yielding mm−1 possibilities. Moreover, at most m − 1 nodes remain in so far that they have not been used as hooks, and they have to be assigned to one of m links, so we can do this in mm−1 ways again. Altogether, the first phase comprises at most m2m−2 alternatives to construct the respective tree. It remains to estimate the number of ways in which 2m leaves can be added to GX . As leaves are singletons (each leaf link in X contains exactly one element from X), we only need to count the number of ways to choose 2m
elements from the set {1, . . . , m} where repetitions are allowed. These are 3m−1 many. All in 2m 3m−1
2m−2 ⊓ ⊔ all, we count m m−1 possibilities to generate a chain mail for X. Lemma 4. Let 1 > ε > 0, N = (V, E, ℓ) be a network, Y ⊆ V a set of terminals with |Y | ≥ 1/ε2 , and X a chain mail for some X with |X| ≤ 1/ε. Optimal Steiner trees for all sets of the form Xi ∪ Y ′ where Xi ∈ X and Y ′ ⊆ Y with |Y ′ | ≤ ε|Y | + 1 can be computed in time
O |X | · (εε (1 − ε)1−ε )−|Y | · 3ε|Y | · n3 . Proof. There are |X | links, and for each link all small subsets of Y have to be considered. By an application of the Stirling formula, these are at most   
−|Y |  |Y | = O εε (1 − ε)1−ε ε|Y | + 1

many. For each combination of a link and such a set the Dreyfus-Wagner algorithm is called, whose running time is bounded by O(31/ε+ε|Y |+1 · n3 ) in any such case. ⊓ ⊔ 7

4

Retrieving the Holy Grail

Having established all the preliminaries, we can now conclude with the central theorem of this paper. Let X = {X1 , . . . , Xr } be a chain mail for a set of nodes X. Without loss of generality, let X1 , . . . , Xr be a sequence of links such that its every prefix forms a tree just as X itself. Consider the following algorithm, which constructs a table of Steiner trees: 1. For every link Xi ∈ X and every Y ′ ⊆ Y where |Y ′ | ≤ ε|Y | + 1, use the Dreyfus-Wagner algorithm to generate an optimal Steiner tree for Y ′ ∪ Xi and save it into the table cell T (Y ′ ∪ Xi ). 2. For s := 2 to |X | do: Let X ′ := X1 ∪ · · · ∪ Xs . Generate a Steiner tree with terminal set Y ′ ∪ X ′ for each Y ′ ⊆ Y where |Y ′ | ≤ sε|Y | + s as follows: Minimize the expression ℓ(T (Y ′′ ∪Xs )+ℓ(T ((Y ′ \Y ′′ )∪(X ′ \Xs ))) over all Y ′′ ⊆ Y ′ with |Y ′′ | ≤ ε|Y |+1 and |Y ′ \ Y ′′ | ≤ (s − 1)ε|Y | + s − 1, keeping the best resulting tree. Save this tree into the table cell T (Y ′ ∪ X ′ ). Theorem 1. Let X be an (ε|Y | + 1)-granular mirror of an optimal Steiner tree T for some terminal set Y and ε < 0.18. Given X , the above algorithm computes an optimal Steiner tree for Y in time 
−|Y | 3  O |X | · 2|Y | · εε (1 − ε)1−ε ·n . Proof. We will reuse the notation from the description of the algorithm. Obviously, the table contains only Steiner trees. The mirror X of T breaks the terminal set into pieces Y1 ∪ · · · ∪ Y|X | = Y . The correctness of the algorithm follows from the fact that for each 1 ≤ s ≤ |X | the trees T (Y ′ ∪ X ′ ) are optimal for Y ′ = Y1 ∪ · · · ∪ Ys and X ′ = X1 ∪ · · · ∪ Xs . In T we have an optimal Steiner tree that contains X, and thus, any optimal Steiner tree for Y ∪ X is a solution to the Steiner tree problem for Y . To see the above fact, note first that it is true for s = 1 if we believe in the correctness of the Dreyfus-Wagner algorithm, and that furthermore all the entries computed in the first phase are optimal. For the induction step, consider T (Y ′ ∪X ′ ) where Y ′ = Y1 ∪· · ·∪Ys and X ′ = X1 ∪· · ·∪Xs . As X is a mirror of the optimal Steiner tree T , there is a subtree T ′ of T that is optimal for Y ′ ∪ X ′ . In contradiction to our claim, suppose that T ′ is cheaper than T (Y ′ ∪X ′ ). Obviously, {X1 , . . . , Xs } is also a mirror of T ′ . Therefore, we can split T ′ at the articulation node that is the only element in Xs−1 ∩ Xs to obtain two optimal Steiner trees for the respective subsets of the terminals. Because ℓ(T ′ ) < ℓ(T (Y ′ ∪ X ′ )), this implies that at least one of both is better than the respective table entry. This contradicts the induction hypothesis. On the running time: A numerical analysis of the bound in Lemma 4 shows that the first phase takes less than O(2|Y | · n3 ) for ε ≤ 0.18. Observe that the precondition |Y | ≥ 1/ε2 can be assumed to be fulfilled without loss of generality, since the running time is O(poly(n)) if |Y | is bounded by a constant. The second phase consists of |X | − 1 < |X | steps. In each of these, all the ′ Y ⊆ Y of limited size must be looked at. These are less than 2|Y | sets. Again, 8

for each Y ′ , we need to go through all bipartitions where the size of the smaller class Y ′′ is at most ε|Y | + 1. As in the proof of Lemma 4, there are no more than   
−|Y |  |Y | = O εε (1 − ε)1−ε ε|Y | + 1 of those. Altogether, the running time of the algorithm is dominated by the second phase and thus bounded by the product of these three values, multiplied by some polynomial which does not exceed n3 . ⊓ ⊔ Note that this runtime bound still holds if X is just a chain mail, but not an (ε|Y | + 1)-granular mirror of any optimal Steiner tree. The above algorithm may just not find an optimal Steiner tree in this case. Corollary 2. Let N = (V, E, ℓ) be a network with k terminals and 0 0 such that (εε (1 − ε)1−ε )−|Y | = O((1 + δ/2)|Y | ). Using the theorem, we thus get a running time of
O |X | · (2 + δ)|Y | · n3 for each chain mail we consider. By Corollary 1, there exists a (1/ε + 1)-granular mirror X of size at most 3/ε for an optimal Steiner tree in our network, whose base set X satisfies |X| ≤ 1/ε. Unfortunately, we do not know how to choose X or even X. However, by Lemma 3, there are no more than    2|X|−2 3|X| − 1 O |X| |X| − 1

different chain mails for a fixed X. Clearly, there are less than n1/ε different sets X ⊆ V with |X| ≤ 1/ε. Thus the total number of chain mails to go through is O(n1/ε ). In total, we get an asymptotic running time of

O n1/ε · |X | · (2 + δ)|Y | · n3 = O (2 + δ)k · poly(n) . ⊓ ⊔

5

Valor and sincerity

In this section, we take a closer look at the influence of ε on the running time. Corollary 2 states that the Steiner tree problem can be solved in time O(ck · poly(n)) for any c > 2 (given that k is sufficiently large, as εk ≥ 1 is a precondition for Lemma 1). However, this bound obscures the combinatorial explosion occuring as ε approaches 0, and we emphatically point out that we cannot expect the algorithm to be applicable for very small ε since it may have to go through too many chain mails. 9

On the other hand, the estimation on the number of chain mails in Lemma 3 is rather rough. In particular, the analysis of the first phase does not exploit the fact that only those nodes from the base set that were not used as hooks need to be distributed to the links later. Moreover, we consider chain mails X of up to 3/ε links, but we have yet to find an instance where such a huge chain mail is required as an appropriate mirror. Let us recall some of the estimations from above, and put them together. For the sake of readability, we write a/ε instead of ⌊a/ε⌋. By Lemma 3, the total number of chain mails to consider is bounded by     n 2/ε−2 3/ε − 1 . · 1/ε 1/ε − 1 1/ε We already know that the running time of the core algorithm is dominated by its second phase, as seen in the proof of Theorem 1. It performs at most  k 1 3/ε · 2k · ε ε (1 − ε)1−ε many steps per chain mail. To exemplify the combinatorial explosion, we give the resulting bounds for several values of ε. Observe that the runtime bound for the second phase given by Theorem 1 includes the expression 2k · (εε (1 − ε)1−ε )−k . This is less than 3k for ε smaller than about 0.1402. In the following table, the number of chain mails per X determines the constant factor in the running time, while the number of node sets X determines the polynomial in the asymptotic bound. ε 1/8 1/20 1/50

chain mails per X

total asymptotic runtime O(2.9152k · n11 ) O(2.4392k · n23 ) O(2.2061k · n53 )

1018

1.0783 · 3.8409 · 1064 2.1172 · 10208

The picture we come across here is not an unknown one. The tireless wanderer has encountered similar phenomena in the wide field of polynomial time approximation schemes (PTAS). In both cases, small ε lead to humongous contants and large exponents for the polynomials. The difference lies in what we try to achieve by choosing smaller and smaller ε. Whereas we try to get the base of the exponential part of the runtime bound as close to two as possible, approxionados crave optimality.

6

Epilogue

In terms of parameterized complexity, the algorithm presented in this paper is the asymptotically fastest solution to the Steiner tree problem today. While our algorithm is only a bit more complicated than the one by Dreyfus and Wagner, the constants hidden in the Landau notation can become very large if ε is chosen too small. This is because we have to go through all the chain mails with
⌊3/ε⌋ n links for all the ⌊1/ε⌋-element subsets of V . While there are only ⌊1/ε⌋ ways to choose an X ⊆ V with |X| = ⌊1/ε⌋, the number of relevant chain mails grows very rapidly in 1/ε, as detailed above. 10

Hence, in practice, our algorithm is very likely to be slower than the DreyfusWagner algorithm for small values of n or k (or if ε is chosen badly). On the other hand, there is plenty potential for improvement, such as omitting sets X or chain mails X that cannot lead to optimal solutions. To enable more precise statements, work is underway on implementing both algorithms for a comparative analysis. Furthermore, we plan on reducing the number of nodes in X and of chain mails X by dynamically adapting the amount of terminals a link is responsible for. One might imagine that the basic technique employed lends itself to generalization. That is, it should be worthwhile to look at graph algorithms using a dynamic programming approach similar to the Dreyfus-Wagner one, and try to choose more than one point of combination in order to balance the size of subproblems. Acknowledgement. The third author wishes to thank Rolf Niedermeier for suggesting this problem. Knights of the LuFGTI Daniel “Gurnemanz” M¨ olle Stefan “Gawan” Richter Peter “Parzival” Rossmanith Historical Note. Did you know? When we weigh the authors’ years of birth according to their respective ratio of contribution, their average yields exactly the date the seminal paper by Dreyfus and Wagner was published.

References 1. M. Bern and P. Plassmann. The steiner problem with edge lengths 1 and 2. Information Processing Letters, 32:171–176, 1989. 2. S. E. Dreyfus and R. A. Wagner. The steiner problem in graphs. Networks, 1:195–207, 1972. 3. S. S. Fedin and A. S. Kulikov. A 2|E|/4 -time algorithm for max-cut. In Zapiski nauchnyh seminarov POMI, volume 293, pages 129–138, 2002. English translation is to appear in Journal of Mathematical Sciences. 4. K. Iwama. and S. Tamaki. Improved upper bounds for 3-sat. Technical Report TR03-053, ECCC Trier, 2003. 5. H. J. Pr¨ omel and A. Steger. The Steiner Tree Problem. Vieweg, 2002. 6. B. Randerath and I. Schiermeyer. Exact algorithms for minimum dominating set. Technical report, Zentrum f¨ ur Angewandte Informatik K¨ oln, Lehrstuhl Speckenmeyer, April 2004. 7. G. Robins and A. Zelikovsky. Improved steiner tree approximation in graphs. In Proceedings of the 11th ACM-SIAM Symposium on Discrete Algorithms, pages 770–779, 2000.

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Fachgruppe Informatik: Jahresbericht 1986 David de Frutos Escrig, Klaus Indermark: Equivalence Relations of NonDeterministic Ianov-Schemes Manfred Nagl: A Software Development Environment based on Graph Technology Claus Lewerentz, Manfred Nagl, Bernhard Westfechtel: On Integration Mechanisms within a Graph-Based Software Development Environment ¨ Reinhard Rinn: Uber Eingabeanomalien bei verschiedenen Inferenzmodellen Werner Damm, Gert D¨ ohmen: Specifying Distributed Computer Architectures in AADL* Gregor Engels, Claus Lewerentz, Wilhelm Sch¨ afer: Graph Grammar Engineering: A Software Specification Method Manfred Nagl: Set Theoretic Approaches to Graph Grammars Claus Lewerentz, Andreas Sch¨ urr: Experiences with a Database System for Software Documents Herbert Klaeren, Klaus Indermark: A New Implementation Technique for Recursive Function Definitions Rita Loogen: Design of a Parallel Programmable Graph Reduction Machine with Distributed Memory J. B¨orstler, U. M¨ oncke, R. Wilhelm: Table compression for tree automata Gabriele Esser, Johannes R¨ uckert, Frank Wagner: Gesellschaftliche Aspekte der Informatik Peter Martini, Otto Spaniol: Token-Passing in High-Speed Backbone Networks for Campus-Wide Environments Thomas Welzel: Simulation of a Multiple Token Ring Backbone Peter Martini: Performance Comparison for HSLAN Media Access Protocols Peter Martini: Performance Analysis of Multiple Token Rings Andreas Mann, Johannes R¨ uckert, Otto Spaniol: Datenfunknetze Andreas Mann, Johannes R¨ uckert: Packet Radio Networks for Data Exchange Andreas Mann, Johannes R¨ uckert: Concurrent Slot Assignment Protocol for Packet Radio Networks W. Kremer, F. Reichert, J. R¨ uckert, A. Mann: Entwurf einer Netzwerktopologie f¨ ur ein Mobilfunknetz zur Unterst¨ utzung des ¨offentlichen Straßenverkehrs Kai Jakobs: Towards User-Friendly Networking Kai Jakobs: The Directory - Evolution of a Standard Kai Jakobs: Directory Services in Distributed Systems - A Survey Martine Sch¨ ummer: RS-511, a Protocol for the Plant Floor

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U. Quernheim: Satellite Communication Protocols - A Performance Comparison Considering On-Board Processing Peter Martini, Otto Spaniol, Thomas Welzel: File Transfer in High Speed Token Ring Networks: Performance Evaluation by Approximate Analysis and Simulation Fachgruppe Informatik: Jahresbericht 1987 Wolfgang Thomas: Automata on Infinite Objects Michael Sonnenschein: On Petri Nets and Data Flow Graphs Heiko Vogler: Functional Distribution of the Contextual Analysis in Block-Structured Programming Languages: A Case Study of Tree Transducers Thomas Welzel: Einsatz des Simulationswerkzeuges QNAP2 zur Leistungsbewertung von Kommunikationsprotokollen Th. Janning, C. Lewerentz: Integrated Project Team Management in a Software Development Environment Joost Engelfriet, Heiko Vogler: Modular Tree Transducers Wolfgang Thomas: Automata and Quantifier Hierarchies Uschi Heuter: Generalized Definite Tree Languages Fachgruppe Informatik: Jahresbericht 1988 G. Esser, J. R¨ uckert, F. Wagner (Hrsg.): Gesellschaftliche Aspekte der Informatik Heiko Vogler: Bottom-Up Computation of Primitive Recursive Tree Functions Andy Sch¨ urr: Introduction to PROGRESS, an Attribute Graph Grammar Based Specification Language J. B¨orstler: Reuse and Software Development - Problems, Solutions, and Bibliography (in German) Kai Jakobs: OSI - An Appropriate Basis for Group Communication? Kai Jakobs: ISO’s Directory Proposal - Evolution, Current Status and Future Problems Bernhard Westfechtel: Extension of a Graph Storage for Software Documents with Primitives for Undo/Redo and Revision Control Peter Martini: High Speed Local Area Networks - A Tutorial P. Davids, Th. Welzel: Performance Analysis of DQDB Based on Simulation Manfred Nagl (Ed.): Abstracts of Talks presented at the WG ’89 15th International Workshop on Graphtheoretic Concepts in Computer Science Peter Martini: The DQDB Protocol - Is it Playing the Game? Martine Sch¨ ummer: CNC/DNC Communication with MAP Martine Sch¨ ummer: Local Area Networks for Manufactoring Environments with hard Real-Time Requirements M. Sch¨ ummer, Th. Welzel, P. Martini: Integration of Field Bus and MAP Networks - Hierarchical Communication Systems in Production Environments G. Vossen, K.-U. Witt: SUXESS: Towards a Sound Unification of Extensions of the Relational Data Model

14

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J. Derissen, P. Hruschka, M.v.d. Beeck, Th. Janning, M. Nagl: Integrating Structured Analysis and Information Modelling A. Maassen: Programming with Higher Order Functions Mario Rodriguez-Artalejo, Heiko Vogler: A Narrowing Machine for Syntax Directed BABEL H. Kuchen, R. Loogen, J.J. Moreno Navarro, M. Rodriguez Artalejo: Graph-based Implementation of a Functional Logic Language Fachgruppe Informatik: Jahresbericht 1989 Vera Jansen, Andreas Potthoff, Wolfgang Thomas, Udo Wermuth: A Short Guide to the AMORE System (Computing Automata, MOnoids and Regular Expressions) Jerzy Skurczynski: On Three Hierarchies of Weak SkS Formulas R. Loogen: Stack-based Implementation of Narrowing H. Kuchen, A. Wagener: Comparison of Dynamic Load Balancing Strategies Kai Jakobs, Frank Reichert: Directory Services for Mobile Communication Kai Jakobs: What’s Beyond the Interface - OSI Networks to Support Cooperative Work Kai Jakobs: Directory Names and Schema - An Evaluation Ulrich Quernheim, Dieter Kreuer: Das CCITT - Signalisierungssystem Nr. 7 auf Satellitenstrecken; Simulation der Zeichengabestrecke H. Kuchen, R. Loogen, J.J. Moreno Navarro, M. Rodriguez Artalejo: Lazy Narrowing in a Graph Machine Kai Jakobs, Josef Kaltwasser, Frank Reichert, Otto Spaniol: Der Computer f¨ahrt mit Rudolf Mathar, Andreas Mann: Analyzing a Distributed Slot Assignment Protocol by Markov Chains A. Maassen: Compilerentwicklung in Miranda - ein Praktikum in funktionaler Programmierung (written in german) Manfred Nagl, Andreas Sch¨ urr: A Specification Environment for Graph Grammars A. Sch¨ urr: PROGRESS: A VHL-Language Based on Graph Grammars Marita M¨ oller: Ein Ebenenmodell wissensbasierter Konsultationen - Unterst¨ utzung f¨ ur Wissensakquisition und Erkl¨ arungsf¨ahigkeit Eric Kowalewski: Entwurf und Interpretation einer Sprache zur Beschreibung von Konsultationsphasen in Expertensystemen Y. Ortega Mallen, D. de Frutos Escrig: A Complete Proof System for Timed Observations Manfred Nagl: Modelling of Software Architectures: Importance, Notions, Experiences H. Fassbender, H. Vogler: A Call-by-need Implementation of Syntax Directed Functional Programming Guenther Geiler (ed.), Fachgruppe Informatik: Jahresbericht 1990 B. Steffen, A. Ingolfsdottir: Characteristic Formulae for Processes with Divergence M. Portz: A new class of cryptosystems based on interconnection networks

15

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H. Kuchen, G. Geiler: Distributed Applicative Arrays Ludwig Staiger: Kolmogorov Complexity and Hausdorff Dimension Ludwig Staiger: Syntactic Congruences for w-languages Eila Kuikka: A Proposal for a Syntax-Directed Text Processing System K. Gladitz, H. Fassbender, H. Vogler: Compiler-based Implementation of Syntax-Directed Functional Programming R. Loogen, St. Winkler: Dynamic Detection of Determinism in Functional Logic Languages K. Indermark, M. Rodriguez Artalejo (Eds.): Granada Workshop on the Integration of Functional and Logic Programming Rolf Hager, Wolfgang Kremer: The Adaptive Priority Scheduler: A More Fair Priority Service Discipline Andreas Fasbender, Wolfgang Kremer: A New Approximation Algorithm for Tandem Networks with Priority Nodes J. B¨orstler, A. Z¨ undorf: Revisiting extensions to Modula-2 to support reusability J. B¨orstler, Th. Janning: Bridging the gap between Requirements Analysis and Design A. Z¨ undorf, A. Sch¨ urr: Nondeterministic Control Structures for Graph Rewriting Systems Matthias Jarke, John Mylopoulos, Joachim W. Schmidt, Yannis Vassiliou: DAIDA: An Environment for Evolving Information Systems M. Jeusfeld, M. Jarke: From Relational to Object-Oriented Integrity Simplification G. Hogen, A. Kindler, R. Loogen: Automatic Parallelization of Lazy Functional Programs Prof. Dr. rer. nat. Otto Spaniol: ODP (Open Distributed Processing): Yet another Viewpoint H. Kuchen, F. L¨ ucking, H. Stoltze: The Topology Description Language TDL S. Graf, B. Steffen: Compositional Minimization of Finite State Systems R. Cleaveland, J. Parrow, B. Steffen: The Concurrency Workbench: A Semantics Based Tool for the Verification of Concurrent Systems Rudolf Mathar, J¨ urgen Mattfeldt: Optimal Transmission Ranges for Mobile Communication in Linear Multihop Packet Radio Networks M. Jeusfeld, M. Staudt: Query Optimization in Deductive Object Bases J. Knoop, B. Steffen: The Interprocedural Coincidence Theorem J. Knoop, B. Steffen: Unifying Strength Reduction and Semantic Code Motion T. Margaria: First-Order theories for the verification of complex FSMs B. Steffen: Generating Data Flow Analysis Algorithms from Modal Specifications Stefan Eherer (ed.), Fachgruppe Informatik: Jahresbericht 1991 Bernhard Westfechtel: Basismechanismen zur Datenverwaltung in strukturbezogenen Hypertextsystemen S. A. Smolka, B. Steffen: Priority as Extremal Probability Matthias Jarke, Carlos Maltzahn, Thomas Rose: Sharing Processes: Team Coordination in Design Repositories

16

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O. Burkart, B. Steffen: Model Checking for Context-Free Processes Matthias Jarke, Klaus Pohl: Information Systems Quality and Quality Information Systems 1992-08 ∗ Rudolf Mathar, J¨ urgen Mattfeldt: Analyzing Routing Strategy NFP in Multihop Packet Radio Networks on a Line 1992-09 ∗ Alfons Kemper, Guido Moerkotte: Grundlagen objektorientierter Datenbanksysteme 1992-10 Matthias Jarke, Manfred Jeusfeld, Andreas Miethsam, Michael Gocek: Towards a logic-based reconstruction of software configuration management 1992-11 Werner Hans: A Complete Indexing Scheme for WAM-based Abstract Machines 1992-12 W. Hans, R. Loogen, St. Winkler: On the Interaction of Lazy Evaluation and Backtracking ∗ 1992-13 Matthias Jarke, Thomas Rose: Specification Management with CAD 1992-14 Th. Noll, H. Vogler: Top-down Parsing with Simultaneous Evaluation on Noncircular Attribute Grammars 1992-15 A. Schuerr, B. Westfechtel: Graphgrammatiken und Graphersetzungssysteme(written in german) ∗ 1992-16 Graduiertenkolleg Informatik und Technik (Hrsg.): Forschungsprojekte des Graduiertenkollegs Informatik und Technik 1992-17 M. Jarke (ed.): ConceptBase V3.1 User Manual 1992-18 ∗ Clarence A. Ellis, Matthias Jarke (Eds.): Distributed Cooperation in Integrated Information Systems - Proceedings of the Third International Workshop on Intelligent and Cooperative Information Systems 1992-19-00 H. Kuchen, R. Loogen (eds.): Proceedings of the 4th Int. Workshop on the Parallel Implementation of Functional Languages 1992-19-01 G. Hogen, R. Loogen: PASTEL - A Parallel Stack-Based Implementation of Eager Functional Programs with Lazy Data Structures (Extended Abstract) 1992-19-02 H. Kuchen, K. Gladitz: Implementing Bags on a Shared Memory MIMDMachine 1992-19-03 C. Rathsack, S.B. Scholz: LISA - A Lazy Interpreter for a Full-Fledged Lambda-Calculus 1992-19-04 T.A. Bratvold: Determining Useful Parallelism in Higher Order Functions 1992-19-05 S. Kahrs: Polymorphic Type Checking by Interpretation of Code 1992-19-06 M. Chakravarty, M. K¨ohler: Equational Constraints, Residuation, and the Parallel JUMP-Machine 1992-19-07 J. Seward: Polymorphic Strictness Analysis using Frontiers (Draft Version) 1992-19-08 D. G¨ artner, A. Kimms, W. Kluge: pi-Redˆ+ - A Compiling GraphReduction System for a Full Fledged Lambda-Calculus 1992-19-09 D. Howe, G. Burn: Experiments with strict STG code 1992-19-10 J. Glauert: Parallel Implementation of Functional Languages Using Small Processes 1992-19-11 M. Joy, T. Axford: A Parallel Graph Reduction Machine 1992-19-12 A. Bennett, P. Kelly: Simulation of Multicache Parallel Reduction ∗

17

1992-19-13 K. Langendoen, D.J. Agterkamp: Cache Behaviour of Lazy Functional Programs (Working Paper) 1992-19-14 K. Hammond, S. Peyton Jones: Profiling scheduling strategies on the GRIP parallel reducer 1992-19-15 S. Mintchev: Using Strictness Information in the STG-machine 1992-19-16 D. Rushall: An Attribute Grammar Evaluator in Haskell 1992-19-17 J. Wild, H. Glaser, P. Hartel: Statistics on storage management in a lazy functional language implementation 1992-19-18 W.S. Martins: Parallel Implementations of Functional Languages 1992-19-19 D. Lester: Distributed Garbage Collection of Cyclic Structures (Draft version) 1992-19-20 J.C. Glas, R.F.H. Hofman, W.G. Vree: Parallelization of Branch-andBound Algorithms in a Functional Programming Environment 1992-19-21 S. Hwang, D. Rushall: The nu-STG machine: a parallelized Spineless Tagless Graph Reduction Machine in a distributed memory architecture (Draft version) 1992-19-22 G. Burn, D. Le Metayer: Cps-Translation and the Correctness of Optimising Compilers 1992-19-23 S.L. Peyton Jones, P. Wadler: Imperative functional programming (Brief summary) 1992-19-24 W. Damm, F. Liu, Th. Peikenkamp: Evaluation and Parallelization of Functions in Functional + Logic Languages (abstract) 1992-19-25 M. Kesseler: Communication Issues Regarding Parallel Functional Graph Rewriting 1992-19-26 Th. Peikenkamp: Charakterizing and representing neededness in functional loginc languages (abstract) 1992-19-27 H. Doerr: Monitoring with Graph-Grammars as formal operational Models 1992-19-28 J. van Groningen: Some implementation aspects of Concurrent Clean on distributed memory architectures 1992-19-29 G. Ostheimer: Load Bounding for Implicit Parallelism (abstract) 1992-20 H. Kuchen, F.J. Lopez Fraguas, J.J. Moreno Navarro, M. Rodriguez Artalejo: Implementing Disequality in a Lazy Functional Logic Language 1992-21 H. Kuchen, F.J. Lopez Fraguas: Result Directed Computing in a Functional Logic Language 1992-22 H. Kuchen, J.J. Moreno Navarro, M.V. Hermenegildo: Independent AND-Parallel Narrowing 1992-23 T. Margaria, B. Steffen: Distinguishing Formulas for Free 1992-24 K. Pohl: The Three Dimensions of Requirements Engineering 1992-25 ∗ R. Stainov: A Dynamic Configuration Facility for Multimedia Communications 1992-26 ∗ Michael von der Beeck: Integration of Structured Analysis and Timed Statecharts for Real-Time and Concurrency Specification 1992-27 W. Hans, St. Winkler: Aliasing and Groundness Analysis of Logic Programs through Abstract Interpretation and its Safety ∗ 1992-28 Gerhard Steinke, Matthias Jarke: Support for Security Modeling in Information Systems Design 1992-29 B. Schinzel: Warum Frauenforschung in Naturwissenschaft und Technik

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A. Kemper, G. Moerkotte, K. Peithner: Object-Orientation Axiomatised by Dynamic Logic Bernd Heinrichs, Kai Jakobs: Timer Handling in High-Performance Transport Systems B. Heinrichs, K. Jakobs, K. Lenßen, W. Reinhardt, A. Spinner: EuroBridge: Communication Services for Multimedia Applications C. Gerlhof, A. Kemper, Ch. Kilger, G. Moerkotte: Partition-Based Clustering in Object Bases: From Theory to Practice J. B¨orstler: Feature-Oriented Classification and Reuse in IPSEN M. Jarke, J. Bubenko, C. Rolland, A. Sutcliffe, Y. Vassiliou: Theories Underlying Requirements Engineering: An Overview of NATURE at Genesis K. Pohl, M. Jarke: Quality Information Systems: Repository Support for Evolving Process Models A. Zuendorf: Implementation of the imperative / rule based language PROGRES P. Koch: Intelligentes Backtracking bei der Auswertung funktionallogischer Programme Rudolf Mathar, J¨ urgen Mattfeldt: Channel Assignment in Cellular Radio Networks Gerhard Friedrich, Wolfgang Neidl: Constructive Utility in Model-Based Diagnosis Repair Systems P. S. Chen, R. Hennicker, M. Jarke: On the Retrieval of Reusable Software Components W. Hans, St.Winkler: Abstract Interpretation of Functional Logic Languages N. Kiesel, A. Schuerr, B. Westfechtel: Design and Evaluation of GRAS, a Graph-Oriented Database System for Engineering Applications Fachgruppe Informatik: Jahresbericht 1992 Patrick Shicheng Chen: On Inference Rules of Logic-Based Information Retrieval Systems G. Hogen, R. Loogen: A New Stack Technique for the Management of Runtime Structures in Distributed Environments A. Z¨ undorf: A Heuristic for the Subgraph Isomorphism Problem in Executing PROGRES A. Kemper, D. Kossmann: Adaptable Pointer Swizzling Strategies in Object Bases: Design, Realization, and Quantitative Analysis Graduiertenkolleg Informatik und Technik (Hrsg.): Graduiertenkolleg Informatik und Technik Matthias Berger: k-Coloring Vertices using a Neural Network with Convergence to Valid Solutions M. Buchheit, M. Jeusfeld, W. Nutt, M. Staudt: Subsumption between Queries to Object-Oriented Databases O. Burkart, B. Steffen: Pushdown Processes: Parallel Composition and Model Checking R. Große-Wienker, O. Hermanns, D. Menzenbach, A. Pollacks, S. Repetzki, J. Schwartz, K. Sonnenschein, B. Westfechtel: Das SUKITS-Projekt: A-posteriori-Integration heterogener CIM-Anwendungssysteme

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Rudolf Mathar, J¨ urgen Mattfeldt: On the Distribution of Cumulated Interference Power in Rayleigh Fading Channels O. Maler, L. Staiger: On Syntactic Congruences for omega-languages M. Jarke, St. Eherer, R. Gallersdoerfer, M. Jeusfeld, M. Staudt: ConceptBase - A Deductive Object Base Manager M. Staudt, H.W. Nissen, M.A. Jeusfeld: Query by Class, Rule and Concept M. Jarke, K. Pohl, St. Jacobs et al.: Requirements Engineering: An Integrated View of Representation Process and Domain M. Jarke, K. Pohl: Establishing Vision in Context: Towards a Model of Requirements Processes W. Hans, H. Kuchen, St. Winkler: Full Indexing for Lazy Narrowing W. Hans, J.J. Ruz, F. Saenz, St. Winkler: A VHDL Specification of a Shared Memory Parallel Machine for Babel K. Finke, M. Jarke, P. Szczurko, R. Soltysiak: Quality Management for Expert Systems in Process Control M. Jarke, M.A. Jeusfeld, P. Szczurko: Three Aspects of Intelligent Cooperation in the Quality Cycle Margit Generet, Sven Martin (eds.), Fachgruppe Informatik: Jahresbericht 1993 M. Lefering: Development of Incremental Integration Tools Using Formal Specifications P. Constantopoulos, M. Jarke, J. Mylopoulos, Y. Vassiliou: The Software Information Base: A Server for Reuse Rolf Hager, Rudolf Mathar, J¨ urgen Mattfeldt: Intelligent Cruise Control and Reliable Communication of Mobile Stations Rolf Hager, Peter Hermesmann, Michael Portz: Feasibility of Authentication Procedures within Advanced Transport Telematics Claudia Popien, Bernd Meyer, Axel Kuepper: A Formal Approach to Service Import in ODP Trader Federations P. Peters, P. Szczurko: Integrating Models of Quality Management Methods by an Object-Oriented Repository Manfred Nagl, Bernhard Westfechtel: A Universal Component for the Administration in Distributed and Integrated Development Environments Patrick Horster, Holger Petersen: Signatur- und Authentifikationsverfahren auf der Basis des diskreten Logarithmusproblems A. Sch¨ urr: PROGRES, A Visual Language and Environment for PROgramming with Graph REwrite Systems A. Sch¨ urr: Specification of Graph Translators with Triple Graph Grammars A. Sch¨ urr: Logic Based Programmed Structure Rewriting Systems L. Staiger: Codes, Simplifying Words, and Open Set Condition Bernhard Westfechtel: A Graph-Based System for Managing Configurations of Engineering Design Documents P. Klein: Designing Software with Modula-3 I. Litovsky, L. Staiger: Finite acceptance of infinite words

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G. Hogen, R. Loogen: Parallel Functional Implementations: Graphbased vs. Stackbased Reduction M. Jeusfeld, U. Johnen: An Executable Meta Model for Re-Engineering of Database Schemas R. Gallersd¨orfer, M. Jarke, K. Klabunde: Intelligent Networks as a Data Intensive Application (INDIA) M. Mohnen: Proving the Correctness of the Static Link Technique Using Evolving Algebras H. Fernau, L. Staiger: Valuations and Unambiguity of Languages, with Applications to Fractal Geometry M. Jarke, K. Pohl, R. D¨ omges, St. Jacobs, H. W. Nissen: Requirements Information Management: The NATURE Approach M. Jarke, K. Pohl, C. Rolland, J.-R. Schmitt: Experience-Based Method Evaluation and Improvement: A Process Modeling Approach St. Jacobs, St. Kethers: Improving Communication and Decision Making within Quality Function Deployment M. Jarke, H. W. Nissen, K. Pohl: Tool Integration in Evolving Information Systems Environments O. Burkart, D. Caucal, B. Steffen: An Elementary Bisimulation Decision Procedure for Arbitrary Context-Free Processes Fachgruppe Informatik: Jahresbericht 1994 Andy Sch¨ urr, Andreas J. Winter, Albert Z¨ undorf: Graph Grammar Engineering with PROGRES Ludwig Staiger: A Tight Upper Bound on Kolmogorov Complexity by Hausdorff Dimension and Uniformly Optimal Prediction Birgitta K¨onig-Ries, Sven Helmer, Guido Moerkotte: An experimental study on the complexity of left-deep join ordering problems for cyclic queries Sophie Cluet, Guido Moerkotte: Efficient Evaluation of Aggregates on Bulk Types Sophie Cluet, Guido Moerkotte: Nested Queries in Object Bases Sophie Cluet, Guido Moerkotte: Query Optimization Techniques Exploiting Class Hierarchies Markus Mohnen: Efficient Compile-Time Garbage Collection for Arbitrary Data Structures Markus Mohnen: Functional Specification of Imperative Programs: An Alternative Point of View of Functional Languages Rainer Gallersd¨orfer, Matthias Nicola: Improving Performance in Replicated Databases through Relaxed Coherency M.Staudt, K.von Thadden: Subsumption Checking in Knowledge Bases G.V.Zemanek, H.W.Nissen, H.Hubert, M.Jarke: Requirements Analysis from Multiple Perspectives: Experiences with Conceptual Modeling Technology M.Staudt, M.Jarke: Incremental Maintenance of Externally Materialized Views P.Peters, P.Szczurko, M.Jeusfeld: Oriented Information Management: Conceptual Models at Work

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Matthias Jarke, Sudha Ram (Hrsg.): WITS 95 Proceedings of the 5th Annual Workshop on Information Technologies and Systems W.Hans, St.Winkler, F.Saenz: Distributed Execution in Functional Logic Programming Jahresbericht 1995 Michael Hanus, Christian Prehofer: Higher-Order Narrowing with Definitional Trees W.Scheufele, G.Moerkotte: Optimal Ordering of Selections and Joins in Acyclic Queries with Expensive Predicates Klaus Pohl: PRO-ART: Enabling Requirements Pre-Traceability Klaus Pohl: Requirements Engineering: An Overview M.Jarke, W.Marquardt: Design and Evaluation of Computer–Aided Process Modelling Tools Olaf Chitil: The Sigma-Semantics: A Comprehensive Semantics for Functional Programs S.Sripada: On Entropy and the Limitations of the Second Law of Thermodynamics Michael Hanus (Ed.): Proceedings of the Poster Session of ALP96 - Fifth International Conference on Algebraic and Logic Programming Michael Hanus (Ed.): Proceedings of the Poster Session of ALP 96 Fifth International Conference on Algebraic and Logic Programming: Introduction and table of contents Ilies Alouini: An Implementation of Conditional Concurrent Rewriting on Distributed Memory Machines Olivier Danvy, Karoline Malmkjær: On the Idempotence of the CPS Transformation V´ıctor M. Gul´ıas, Jos´e L. Freire: Concurrent Programming in Haskell S´ebastien Limet, Pierre R´ety: On Decidability of Unifiability Modulo Rewrite Systems Alexandre Tessier: Declarative Debugging in Constraint Logic Programming Reidar Conradi, Bernhard Westfechtel: Version Models for Software Configuration Management C.Weise, D.Lenzkes: A Fast Decision Algorithm for Timed Refinement R.D¨ omges, K.Pohl, M.Jarke, B.Lohmann, W.Marquardt: PROART/CE* — An Environment for Managing the Evolution of Chemical Process Simulation Models K.Pohl, R.Klamma, K.Weidenhaupt, R.D¨omges, P.Haumer, M.Jarke: A Framework for Process-Integrated Tools R.Gallersd¨orfer, K.Klabunde, A.Stolz, M.Eßmajor: INDIA — Intelligent Networks as a Data Intensive Application, Final Project Report, June 1996 H.Schimpe, M.Staudt: VAREX: An Environment for Validating and Refining Rule Bases M.Jarke, M.Gebhardt, S.Jacobs, H.Nissen: Conflict Analysis Across Heterogeneous Viewpoints: Formalization and Visualization Manfred A. Jeusfeld, Tung X. Bui: Decision Support Components on the Internet

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Manfred A. Jeusfeld, Mike Papazoglou: Information Brokering: Design, Search and Transformation P.Peters, M.Jarke: Simulating the impact of information flows in networked organizations Matthias Jarke, Peter Peters, Manfred A. Jeusfeld: Model-driven planning and design of cooperative information systems G.de Michelis, E.Dubois, M.Jarke, F.Matthes, J.Mylopoulos, K.Pohl, J.Schmidt, C.Woo, E.Yu: Cooperative information systems: a manifesto S.Jacobs, M.Gebhardt, S.Kethers, W.Rzasa: Filling HTML forms simultaneously: CoWeb architecture and functionality M.Gebhardt, S.Jacobs: Conflict Management in Design Michael Hanus, Frank Zartmann (eds.): Jahresbericht 1996 Johannes Faassen: Using full parallel Boltzmann Machines for Optimization Andreas Winter, Andy Sch¨ urr: Modules and Updatable Graph Views for PROgrammed Graph REwriting Systems Markus Mohnen, Stefan Tobies: Implementing Context Patterns in the Glasgow Haskell Compiler S.Gruner: Schemakorrespondenzaxiome unterst¨ utzen die paargrammatische Spezifikation inkrementeller Integrationswerkzeuge Matthias Nicola, Matthias Jarke: Design and Evaluation of Wireless Health Care Information Systems in Developing Countries Petra Hofstedt: Taskparallele Skelette f¨ ur irregul¨ar strukturierte Probleme in deklarativen Sprachen Dorothea Blostein, Andy Sch¨ urr: Computing with Graphs and Graph Rewriting Carl-Arndt Krapp, Bernhard Westfechtel: Feedback Handling in Dynamic Task Nets Matthias Nicola, Matthias Jarke: Integrating Replication and Communication in Performance Models of Distributed Databases R. Klamma, P. Peters, M. Jarke: Workflow Support for Failure Management in Federated Organizations Markus Mohnen: Optimising the Memory Management of Higher-Order Functional Programs Roland Baumann: Client/Server Distribution in a Structure-Oriented Database Management System George Botorog: High-Level Parallel Programming and the Efficient Implementation of Numerical Algorithms Fachgruppe Informatik: Jahresbericht 1997 Stefan Gruner, Manfred Nagel, Andy Sch¨ urr: Fine-grained and Structure-Oriented Document Integration Tools are Needed for Development Processes Stefan Gruner: Einige Anmerkungen zur graphgrammatischen Spezifikation von Integrationswerkzeugen nach Westfechtel, Janning, Lefering und Sch¨ urr O. Kubitz: Mobile Robots in Dynamic Environments Martin Leucker, Stephan Tobies: Truth - A Verification Platform for Distributed Systems

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2000-08 2001-01 2001-02 2001-03

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Matthias Oliver Berger: DECT in the Factory of the Future M. Arnold, M. Erdmann, M. Glinz, P. Haumer, R. Knoll, B. Paech, K. Pohl, J. Ryser, R. Studer, K. Weidenhaupt: Survey on the Scenario Use in Twelve Selected Industrial Projects H. Aust: Sprachverstehen und Dialogmodellierung in nat¨ urlichsprachlichen Informationssystemen Th. Lehmann: Geometrische Ausrichtung medizinischer Bilder am Beispiel intraoraler Radiographien M. Nicola, M. Jarke: Performance Modeling of Distributed and Replicated Databases Ansgar Schleicher, Bernhard Westfechtel, Dirk J¨ager: Modeling Dynamic Software Processes in UML W. Appelt, M. Jarke: Interoperable Tools for Cooperation Support using the World Wide Web Klaus Indermark: Semantik rekursiver Funktionsdefinitionen mit Striktheitsinformation Jahresbericht 1998 F. Huch: Verifcation of Erlang Programs using Abstract Interpretation and Model Checking — Extended Version R. Gallersd¨orfer, M. Jarke, M. Nicola: The ADR Replication Manager Mar´ıa Alpuente, Michael Hanus, Salvador Lucas, Germ´ an Vidal: Specialization of Functional Logic Programs Based on Needed Narrowing W. Thomas (Ed.): DLT 99 - Developments in Language Theory Fourth International Conference Kai Jakobs, Klaus-Dieter Kleefeld: Informationssysteme f¨ ur die angewandte historische Geographie Thomas Wilke: CTL+ is exponentially more succinct than CTL Oliver Matz: Dot-Depth and Monadic Quantifier Alternation over Pictures Jahresbericht 1999 Jens V¨ oge, Marcin Jurdzinski: A Discrete Strategy Improvement Algorithm for Solving Parity Games Andreas Becks, Stefan Sklorz, Matthias Jarke: Exploring the Semantic Structure of Technical Document Collections: A Cooperative Systems Approach Mareike Schoop: Cooperative Document Management Mareike Schoop, Christoph Quix (eds.): Proceedings of the Fifth International Workshop on the Language-Action Perspective on Communication Modelling Markus Mohnen, Pieter Koopman (Eds.): Proceedings of the 12th International Workshop of Functional Languages Thomas Arts, Thomas Noll: Verifying Generic Erlang Client-Server Implementations Jahresbericht 2000 Benedikt Bollig, Martin Leucker: Deciding LTL over Mazurkiewicz Traces Thierry Cachat: The power of one-letter rational languages

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2001-04 2001-05 2001-06 2001-07 2001-08

2001-09 2001-10 2001-11 2002-01 2002-02

∗

2002-03 2002-04 2002-05 2002-06

2002-07 2002-08 2002-09 2002-10 2002-11 2003-01 2003-02

∗

2003-03 2003-04 2003-05 2003-06 2003-07

2003-08 2004-01

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Benedikt Bollig, Martin Leucker, Michael Weber: Local Parallel Model Checking for the Alternation Free mu-Calculus Benedikt Bollig, Martin Leucker, Thomas Noll: Regular MSC Languages Achim Blumensath: Prefix-Recognisable Graphs and Monadic SecondOrder Logic Martin Grohe, Stefan W¨ohrle: An Existential Locality Theorem Mareike Schoop, James Taylor (eds.): Proceedings of the Sixth International Workshop on the Language-Action Perspective on Communication Modelling Thomas Arts, J¨ urgen Giesl: A collection of examples for termination of term rewriting using dependency pairs Achim Blumensath: Axiomatising Tree-interpretable Structures Klaus Indermark, Thomas Noll (eds.): Kolloquium Programmiersprachen und Grundlagen der Programmierung Jahresbericht 2001 J¨ urgen Giesl, Aart Middeldorp: Transformation Techniques for ContextSensitive Rewrite Systems Benedikt Bollig, Martin Leucker, Thomas Noll: Generalised Regular MSC Languages J¨ urgen Giesl, Aart Middeldorp: Innermost Termination of ContextSensitive Rewriting Horst Lichter, Thomas von der Maßen, Thomas Weiler: Modelling Requirements and Architectures for Software Product Lines Henry N. Adorna: 3-Party Message Complexity is Better than 2-Party Ones for Proving Lower Bounds on the Size of Minimal Nondeterministic Finite Automata J¨ org Dahmen: Invariant Image Object Recognition using Gaussian Mixture Densities Markus Mohnen: An Open Framework for Data-Flow Analysis in Java Markus Mohnen: Interfaces with Default Implementations in Java Martin Leucker: Logics for Mazurkiewicz traces J¨ urgen Giesl, Hans Zantema: Liveness in Rewriting Jahresbericht 2002 J¨ urgen Giesl, Ren´e Thiemann: Size-Change Termination for Term Rewriting J¨ urgen Giesl, Deepak Kapur: Deciding Inductive Validity of Equations J¨ urgen Giesl, Ren´e Thiemann, Peter Schneider-Kamp, Stephan Falke: Improving Dependency Pairs Christof L¨oding, Philipp Rohde: Solving the Sabotage Game is PSPACEhard Franz Josef Och: Statistical Machine Translation: From Single-Word Models to Alignment Templates Horst Lichter, Thomas von der Maßen, Alexander Nyßen, Thomas Weiler: Vergleich von Ans¨ atzen zur Feature Modellierung bei der Softwareproduktlinienentwicklung J¨ urgen Giesl, Ren´e Thiemann, Peter Schneider-Kamp, Stephan Falke: Mechanizing Dependency Pairs Fachgruppe Informatik: Jahresbericht 2004

25

2004-02 2004-03 2004-04 2004-05 2004-06 2004-07 2004-08 2004-09 2004-10 2005-01 2005-02

2005-03

∗

∗

Benedikt Bollig, Martin Leucker: Message-Passing Automata are expressively equivalent to EMSO logic Delia Kesner, Femke van Raamsdonk, Joe Wells (eds.): HOR 2004 – 2nd International Workshop on Higher-Order Rewriting Slim Abdennadher, Christophe Ringeissen (eds.): RULE 04 – Fifth International Workshop on Rule-Based Programming Herbert Kuchen (ed.): WFLP 04 – 13th International Workshop on Functional and (Constraint) Logic Programming Sergio Antoy, Yoshihito Toyama (eds.): WRS 04 – 4th International Workshop on Reduction Strategies in Rewriting and Programming Michael Codish, Aart Middeldorp (eds.): WST 04 – 7th International Workshop on Termination Klaus Indermark, Thomas Noll: Algebraic Correctness Proofs for Compiling Recursive Function Definitions with Strictness Information Joachim Kneis, Daniel M¨ olle, Stefan Richter, Peter Rossmanith: Parameterized Power Domination Complexity Zinaida Benenson, Felix C. G¨artner, Dogan Kesdogan: Secure MultiParty Computation with Security Modules Fachgruppe Informatik: Jahresbericht 2005 Maximillian Dornseif, Felix C. G¨artner, Thorsten Holz, Martin Mink: An Offensive Approach to Teaching Information Security: Aachen Summer School Applied IT Security J¨ urgen Giesl, Ren´e Thiemann, Peter Schneider-Kamp: Proving and Disproving Termination of Higher-Order Functions

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Please contact [email protected] to obtain copies.

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