In 1934 Cartan visited Moscow and lectured in the Mechanics and Mathematics Faculty. Pontryagin attended Cartan 's lecture which was in French but Pontryagin did not understand French so he listened to a whispered translation by Nina Bari who sat beside him. Cartan 's lecture was based around the problem of calculating the homology groups of the classical compact Lie groups. Cartan had some ideas how this might be achieved and he explained these in the lecture but, the following year, Pontryagin was able to solve the problem completely using a totally different approach to the one suggested by Cartan .
Sa 1934 Cartan binisita ng Moscow at lectured sa mechanics at Mathematics Faculty. Pontryagin dinaluhan Cartan 's panayam na kung saan ay sa French Pontryagin ngunit hindi maintindihan French kaya siya listened sa isang whispered translation by Nina Bari na Sabado sa tabi niya. Cartan 's panayam ay batay sa paligid ang mga problema ng pagkalkula ng homology grupo ng mga klasiko compact humiga / magsinungaling grupo. Cartan nagkaroon ng ilang mga ideya kung paano maaaring ito makakamtan at ipinaliwanag niya ang mga ito sa mga panayam ngunit, ang mga sumusunod na mga taon, Pontryagin ay able sa lutasin ang problema sa ganap na gamit ang isang ganap na iba't-ibang pamamaraan upang ang isang iminumungkahing Cartan sa pamamagitan ng.