We consider the Top-k Approximate Subtree Matching (TASM) problem: finding the k best matches of a small query tree, e.g., a DBLP article with 15 nodes, in a large document tree, e.g., DBLP with 26M nodes, using the canonical tree edit distance as a similarity measure between subtrees. Evaluating the tree edit distance for large XML trees is difficult: the best known algorithms have cubic runti...

In this thesis we use a knowledge-based approach to disambiguating prepositional phrase attachments in English sentences. This method was first introduced by S. M. Harabagiu. The Penn Treebank corpus is used as the training text. We extract 4-tuples of the form [ V P , NP1, Prep, NP2 ] and sort them into classes according to the semantic relationships between parts of each tuple. These relation...

We consider the problem of structure prediction for sparse LU factorization with partial pivoting. In this context, it is well known that the column elimination tree plays an important role for matrices satisfying an irreducibility condition, called the strong Hall property. Our primary goal in this paper is to address the structure prediction problem for matrices satisfying a weaker assumption...

Ontologien und Taxonomien sind kontrollierte, strukturierte Vokabulare für eine Domäne um Objekte darin zu beschreiben. Ontologien in der Biologie, wie beispielsweise die NCBI Taxonomie, die Klassifizierung von Lebewesen, oder die Gene Ontology sind als Bäume bzw. gerichtete, azyklische Graphen aufgebaut. Taxonomien werden häufig zusammen mit den annotierten Objekten in relationalen Datenbanken...

In this paper we present a new functional traversal abstraction for processing OO data structures that decomposes traversal computation into three function objects and a traversal control function. Function objects compute and combine values over a general traversal while the control function allows programmers to limit the extent of a traversal. Our new abstraction is supported by a Java libra...

In many applications the desired outcome of satisfiability checking is that the formula is unsatisfiable: A satisfying assignment essentially exhibits a bug and unsatisfiability implies a lack of bugs, at least for the property being verified. Current high-performance satisfiability checkers are unable to provide proof of unsatisfiability. Since bugs have been discovered in many solvers long af...