This special issue contains a selective collection of carefully refereed papers based on talks presented during the 15th Baikal International School-Seminar on Optimization methods and their applications held during June 23-29, 2011 and dedicated to the memory of Valerian P. Bulatov (1935-2010), who made a number of important contributions to the different helds of optimization and who played a leading role in organization of Baikal conferences. These papers deal with both theoretical and practical aspects of optimization.

This special issue contains a selective collection of carefully refereed papers based on talks presented during the 15th Baikal International School-Seminar on Optimization methods and their applications held during June 23-29, 2011 and dedicated to the memory of Valerian P. Bulatov (1935-2010), who made a number of important contributions to the different helds of optimization and who played a leading role in organization of Baikal conferences. These papers deal with both theoretical and practical aspects of optimization.