Matthias Schork

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A new family of generalized Stirling and Bell numbers is introduced by considering powers (V U)n of the noncommuting variables U, V satisfying UV = V U +hV s. The case s = 0 (and h = 1) corresponds to the conventional Stirling numbers of second kind and Bell numbers. For these generalized Stirling numbers, the recursion relation is given and explicit(More)
Recently the vertex Padmakar–Ivan (PI v) index of a graph G was introduced as the sum over all edges e = uv of G of the number of vertices which are not equidistant to the vertices u and v. In this paper the vertex PI index and Szeged index of bridge graphs are determined. Using these formulas, the vertex PI indices and Szeged indices of several graphs are(More)
In theoretical chemistry molecular structure descriptors also called topological indices are used to understand physico-chemical properties of chemical compounds. By now there do exist a lot of different types of such indices which capture different aspects of the molecular graphs associated to the molecules considered. Arguably the most famous such index(More)
The generalized Stirling numbers introduced recently [11, 12] are considered in detail for the particular case s = 2 corresponding to the meromorphic Weyl algebra. A combinatorial interpretation in terms of perfect matchings is given for these meromorphic Stirling numbers and the connection to Bessel functions is discussed. Furthermore, two related(More)
It is shown that the determinants of the correlation functions of the generalized bc-system introduced recently are given as pullbacks of the non-abelian theta divisor. The usual bc-system appearing in bosonic string theory 1;2 is very well understood 1?4 and has also been considered in a rigorous algebro-geometric way by Raina 5;6. Assuming some natural(More)