Higher Order Logic. A proof-generating system for {higher order logic} based on {LCF}. Implementations include {HOL-88} and HOL-90. . Mailing list: info-hol@ted.cs.uidaho.edu. ["HOL: A Machine Oriented Formulation of Higher Order Logic", M.J.C. Gordon, Report 68, Comp Lab U Cambridge (1985)]. ["Introduction to HOL", M.J.C. Gordon et al, Cambridge U Press 1993 ISBN 0-521-441897].