### Biography

Victor Neumann Lara,** **Mexican** **mathematician (Huejutla de Reyes, Hidalgo State 06 June 1933 – Puebla 26 February 2004)

From German father

Introduced the notion of dichromatic number of a digraph and the definition of the chromatic number of a digraph (1982)

With L. Montejano proved a Mengerian theorem for long paths (1984)

With J. Urrutia showed that in any set of n points in the plane in general position there is always a pair of points such that any circle through them contains at least n=2 points (1985)

With E. Rivera Campo proved a Chvátal-Erdos type theorem concerning the existence of a spanning m-tree (1991)

With I. Puga Espinosa gave necessary and sufficient conditions for a dendroid to be a dendrite (1993)

With S. Hazan proved that every finite partially ordered set whose comparability graph is clique null has the fixed point property (1996)

Conjectured the existence of infinite families of vertex critical-r-dichromatic circulant tournaments (1997)

Introduced acyclic disconnection of a digraph (1999)

With F. Larrión & M.A. Pizaña showed that almost all closed surfaces admit a Whitney triangulation whose underlying graph is clique convergent (2003)

With J.J. Montellano-Ballesteros proved the conjecture of anti-Ramsey number by cycles completely (2005)

With F. Larrión & M.A. Pizaña proved that each closed surface admits a clique divergent triangulation (2006)

With M. Olsen introduced the concept of molds

With R.G. Wilson proved that the nonexistence of infinite paths was a necessary and sufficient condition for the existence of a compact compatible topology on a tree

Eponym of Neumann Lara retraction theorem