Gottfried Tinhofer

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Synopsis The mathematical basis of graph set analysis of hydrogen-bond patterns in crystals is presented by deening terms and developing tools for its treatment and subsequent implementation in suitable software algorithms. Abstract To provide a foundation for further theoretical and software development of the application of graph sets to patterns of(More)
Let (G;) be a permutation group of degree n. Let V (G;) be the set of all square matrices of order n which commute with all permutation matrices corresponding to permutations from (G;): V (G;) is a matrix algebra which is called the centralizer algebra of (G;): In this paper we introduce the combinatorial analogue of centralizer algebras, namely coherent(More)
This paper deals with graph invariants and stabilization procedures. We consider colored graphs and their automorphisms and we discuss the isomorphism problem for such graphs. Various global and local isomorphism invariants are introduced. We study canonical num-berings, invariant partitions, stable and equitable partitions and algorithms for stabilizing(More)
1 Abstract In this paper we present a time-polynomial recognition algorithm for circulant graphs of prime order. A circulant graph G of order n is a Cayley graph over the cyclic group Z n : Equivalently, G is circulant ii its vertices can be ordered such that the corresponding adjacency matrix becomes a circulant matrix. To each circulant graph we may(More)
1 Abstract A coherent algebra is a matrix algebra over the eld of the complex numbers which is closed under conjugate transposition and elementwise multiplication of matrices and which contains the identity matrix and the all 1 matrix. This algebraic structure has a variety of important applications. Among others, coherent algebras are an appropriate tool(More)
  • W Hochstt, G Tinhofer, Winfried Hochstt, W Hochstt Attler, Vor Kurzem, Haben R Jamison
  • 1993
Zusammenfassung Hamiltonicity in graphs with few P 4 's. In a recent series of articles R. Jamison and S. Olariu developed, starting from an extension of the notion of a cograph, a theory of the decomposition of graphs into P 4-connected components. It turned out in their work that the algorithmic idea to exploit the unique tree structure of cographs can be(More)