00270    a2200097   4500020001500000082001800015245005600033260004000089300001500129650002800144  a033514277X  a004.0151bOPE  aChapter 8 binary relationsbBlock IV (Chapters 4-6)  aWaltonbOpen Universityc1988g1988  a51p.c29cm  aMathematical principles