@article{CTGDC_1981__22_3_329_0, author = {Frei, Armin}, title = {On the preservation of homotopy invariance by {Kan} extensions}, journal = {Cahiers de topologie et g\'eom\'etrie diff\'erentielle}, pages = {329--336}, publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS}, volume = {22}, number = {3}, year = {1981}, mrnumber = {649080}, zbl = {0486.18006}, language = {en}, url = {http://www.numdam.org/item/CTGDC_1981__22_3_329_0/} }