***************************************************************************** * * * The code in this directory is based on material in the paper * * * * G. Nadathur and D. Miller, Higher-Order Logic Programming, in * * Handbook of Logic in Artificial Intelligence and Logic * * Programming, D. M. Gabbay, C. J. Hogger and J. A. Robinson (eds.), * * Oxford University Press, January 1998, pages 499--590. * * * * The adaptation to Teyjus code is due to Gopalan Nadathur. * * * ***************************************************************************** The important conceptual content of the code is the use of higher-order abstract syntax in representing quantification structure in formulas and of beta reduction, higher-order unification and the scoping primitives in probing this structure. The contents of particular files are as follows: lists.sig, Interface and defining code for a collection lists.mod of list manipulation predicates logic_types.sig A file defining the kinds used in the encoding of a first-order logic logic_basic.sig A file defining the constructors used in encoding the logical symbols logic_vocab.sig A file encoding the nonlogical vocabulary for a first-order logic hc_interp.sig A interpreter for Horn clauses logic hc_interp.mod hcinterp_examples.sig Code for testing out the Horn clause logic hcinterp_examples.mod interpreter refl_syntax.sig Files defining the signature and clauses refl_syntax.mod for recognizing quantifier free expressions in the logic hc_syntax.sig Files defining the signature and clauses hc_syntax.mod for recognizing goals and definite clauses in the Horn clause fragment of logic hcsyntax_examples.sig Code for testing out the Horn clause logic hcsyntax_examples.mod recognizers pnf.sig A prenex normal form transformer for pnf.mod formulas pnf_examples.sig Code for testing out the prenex-normal form pnf_examples.mod transformer script1, Scripts exhibiting the compilation and execution script2, of the code for the Horn clause interpreter, script3 formula recognizer and prenex normal form transformer