00299nam a2200109 a 450000500170000002000150001708200200003210000160005224500530006826000500012130000180017120251203091810.0  a0818689951  a006.33,bD, Val  aUma G.Gupta  aValidating and verifying knowledge-based systems  aCaliforniabIEEE computer society Pressc1990  aix,409p, 26cm