In the years between 1931 and 1941 de Beauvoir continued living with her Grandmother while teaching at a number of Lycées in Marseille, Rouen and Paris. She was professor at the Sorbonne from 1941 to 1943. Her work allowed her to be financially independent. She gathered a number of friends around her, and spent time in the cafes of Paris writing and giving talks. She went to study German philosophy in Berlin for a while, remaining in touch with Sartre all the time. At one point they would form a kind of love triangle with a student at de Beauvoir's lycée named Olga Kosakievicz. De Beauvoir based her first book of fiction, L'Invitée (She Came To Stay, 1943), on the experience of living with the third party so close to her relationship with Sartre. The novel is influenced by the philosophy of Hegel, Heidegger, and Kojeve, which both she and Sartre were studying at the time. It examines the problem of choice in an absurd world, and the relationship of an individual conscience to "the other". Her writing is also viewed as influenced by existentialism, although she would persistently resist the title of "existentialist" despite her links to Sartre.