**
Volume 16 (2005), Issue No. 3**

Foreword

X. M. Ren, Y. Wang and K. P. Shum:
On finding the generalized inverse matrix for the product of matrices

M. Barnabei, F. Bonetti and M. Silimbani:
An algorithmic approach to maximal unions of chains in a partially ordered set

Yi Zhi Chen and Yonghua Li:
Perfect wrpp semigroups

L. Ferrari and R. Pinzani:
Catalan-like numbers and succession rules

A. Frosini and M. Nivat:
On a tomographic equivalence between (0, 1) matrices

A. Gagarin, G. Labelle and P. Leroux:
The structure and labelled enumeration of K_{3,3}
-subdivision-free projective-planar graphs

A. Khosravi and B. Khosravi:
Two new characterizations for sporadic simple groups

G. Louchard, C. Marini, F. Montagna and G. Simi:
A variant of the Guessing Secrets game

S. Nenthein, P. Youngkhong and Y. Kemprasit:
Regular elements of some transformation semigroups