On a theorem by Hoffman and Ramsay

A q-Analogue of Graham, Hoffman and Hosoya's Theorem

Graham, Hoffman and Hosoya gave a very nice formula about the determinant of the distance matrix DG of a graph G in terms of the distance matrix of its blocks. We generalize this result to a q-analogue of DG. Our generalization yields results about the equality of the determinant of the mod-2 (and in general mod-k) distance matrix (i.e. each entry of the distance matrix is taken modulo 2 or k) ...

ö[ ELEMENTARY PROOF OF THE WI ELAN DT-HOFFMAN THEOREM « AND OF ITS GENERALIZATION BY

An elementary proof is given of the Wielandt-Hofftnan Theorem for normal matrices and of a generalization of this theorem. The proof makes no direct appeal to results fron linearprogramming theory. Reproduction in whole or in part is permitted for any purpose of the United States Government, Division of Numerical and Applied Mathematics) National Physical Laboratory, Teddington, Middlesex, Engl...

On a Conjecture of a . J . Hoffman

The following question was recently raised by A. J. Hoffman [2]: "If P is a d-polytope, i>0 an integer and &,••*, C* closed convex sets in P, such that every /-flat that meets P meets Uf=i d; do there exist polytopes Di, • • • , Dk, with DiQd for all 1 ̂ i^k, such that if a ¿-flat meets P, it meets Uf_x 7>,?" The purpose of this note is to give a counterexample to this conjecture, with d = 3, t ...

A Remark on a Remark by Macaulay or Enhancing Lazard Structural Theorem

a study on insurer solvency by panel data model: the case of iranian insurance market

the aim of this thesis is an approach for assessing insurer’s solvency for iranian insurance companies. we use of economic data with both time series and cross-sectional variation, thus by using the panel data model will survey the insurer solvency.