Hard diffraction in events with dijets and rapidity gaps has been studied by
D\O and CDF for three processes: hard color singlet exchange, hard single
diffraction, and hard double pomeron exchange, using Tevatron pˉp data at
s = 630 GeV and 1.8 TeV. Measurements of rates, η,ET and
s dependencies are presented and comparisons made with predictions of
several models.Comment: Presented at DPF99, 8 pages, 6 figure