We continue the study of finite connected edge-bipartite graphs Δ, with m≥ 2 vertices (a
class of signed graphs), started in [SIAM J. Discrete Math. 27 (2013), 827-854] and …

We continue the study of finite connected loop-free edge-bipartite graphs Δ, with m≥ 3
vertices (a class of signed graphs), we started in Simson (2013)[48] and M. Gąsiorek et …

Cartan matrices and quasi-Cartan matrices play an important role in such areas as Lie
theory, representation theory, and algebraic graph theory. It is known that each (connected) …

Cartan matrices, quasi-Cartan matrices and associated integral quadratic forms and root
systems play an important role in such areas like Lie theory, representation theory and …

We study a class of signed graphs called finite connected loop-free edge-bipartite graphs Δ
(bigraphs, for short), started in Simson (2013) and continued in Simson and Zając (2017) …

We continue the study of a class of signed graphs called finite connected loop-free edge-
bipartite graphs Δ (bigraphs, for short), started in Simson (2013)[33] and continued in …

Cartan matrices, quasi-Cartan matrices and associated upper triangular Gram matrices
control important combinatorial aspects of Lie theory and representation theory of …

For standard algorithms verifying positive definiteness of a matrix $ A\in\mathbb {M} _n
(\mathbb {R}) $ based on Sylvester's criterion, the computationally pessimistic case is this …