Using the No-Search Easy-Hard Technique for Downward Collapse

Σ k Π k DIFFm(Σ p k ) coDIFFm(Σ p k ) P Σ p k m-tt P Σ p k m+1-tt BH(Σ k ) Supported in part by grants NSF-CCR-9322513, NSF-INT-9513368/DAAD-315-PRO-fo-ab, and NSF-INT9815095/DAAD-315-PPP-gü-ab, and a NATO Postdoctoral Science Fellowship from the DAAD’s “Gemeinsames Hochschulsonderprogramm III von Bund und Ländern” program. This report combines and extends each of technical reports corr-cs.CC/9808002 and corr-cs.CC/9910008. Email: [email protected]. Work done in part while visiting Friedrich-Schiller-Universität and Julius-MaximiliansUniversität. Email: [email protected]. Work done in part while visiting Friedrich-Schiller-Universität and JuliusMaximilians-Universität. Email: [email protected]. Work done in part while visiting Le Moyne College, and while visiting the University of Rochester under a NATO Postdoctoral Science Fellowship from the DAAD.