@article{RO_2020__54_4_1027_0, author = {Mojdeh, Doost Ali and Samadi, Babak and Yero, Ismael G.}, title = {Global defensive $k$-alliances in directed graphs: combinatorial and computational issues}, journal = {RAIRO - Operations Research - Recherche Op\'erationnelle}, pages = {1027--1040}, publisher = {EDP-Sciences}, volume = {54}, number = {4}, year = {2020}, doi = {10.1051/ro/2019049}, mrnumber = {4100699}, language = {en}, url = {http://www.numdam.org/articles/10.1051/ro/2019049/} }