He was able to find a post in the new Slovak Technical University in Bratislava and he taught there until 1944 publishing a 64 page work Theory of Semigroups in 1943. However the Germans had taken over the whole country after May 1942 and mass executions followed.
Siya ay kakayahang makahanap ng isang post sa bagong Slovak Technical University in Bratislava at siya nagtuturo mayroon hanggang 1944-publish ng isang 64 na pahina sa trabaho teorya ng Semigroups sa 1943. Subalit ang mga Germans ay kinuha sa buong bansa pagkatapos ng Mayo 1942 at mass executions sinundan.