sentences:  In 1972, Per Enflo constructed a separable Banach space that lacks the approximation property and a Schauder basis.In 1972, Mazur awarded a live goose to Enflo in a ceremony at the Stefan Banach Center in Warsaw; the "goose reward" ceremony was broadcast throughout Poland.In functional analysis, one of the most prominent problems was the invariant subspace problem, which required the evaluation of the truth of the following proposition