All real little girls' dresses from the '20s to the '60s had been crotch-length.
All authentic little girls' dresses from the '20s to the '60s were floor length.
mnli hypothesis: All authentic little girls' dresses from the '20s to the '60s were floor length. premise: All real little girls' dresses from the '20s to the '60s had been crotch-length.