@article { author = {}, title = {Preface}, journal = {Communications in Combinatorics and Optimization}, volume = {4}, number = {2}, pages = {-}, year = {2019}, publisher = {Azarbaijan Shahid Madani University}, issn = {2538-2128}, eissn = {2538-2136}, doi = {}, abstract = {}, keywords = {}, url = {http://comb-opt.azaruniv.ac.ir/article_14246.html}, eprint = {http://comb-opt.azaruniv.ac.ir/article_14246_269d7ac6efb0c5c1f3921316e8277681.pdf} }