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src/FOLP/ex/quant.ML

author | wenzelm |

Mon, 22 Jun 1998 15:09:59 +0200 | |

changeset 5061 | f947332d5465 |

parent 3836 | f1a1817659e6 |

child 15531 | 08c8dad8e399 |

permissions | -rw-r--r-- |

isatool fixgoal;

(* Title: FOLP/ex/quant.ML ID: $Id$ Author: Lawrence C Paulson, Cambridge University Computer Laboratory Copyright 1991 University of Cambridge First-Order Logic: quantifier examples (intuitionistic and classical) Needs declarations of the theory "thy" and the tactic "tac" *) writeln"File FOLP/ex/quant.ML"; Goal "?p : (ALL x y. P(x,y)) --> (ALL y x. P(x,y))"; by tac; result(); Goal "?p : (EX x y. P(x,y)) --> (EX y x. P(x,y))"; by tac; result(); (*Converse is false*) Goal "?p : (ALL x. P(x)) | (ALL x. Q(x)) --> (ALL x. P(x) | Q(x))"; by tac; result(); Goal "?p : (ALL x. P-->Q(x)) <-> (P--> (ALL x. Q(x)))"; by tac; result(); Goal "?p : (ALL x. P(x)-->Q) <-> ((EX x. P(x)) --> Q)"; by tac; result(); writeln"Some harder ones"; Goal "?p : (EX x. P(x) | Q(x)) <-> (EX x. P(x)) | (EX x. Q(x))"; by tac; result(); (*6 secs*) (*Converse is false*) Goal "?p : (EX x. P(x)&Q(x)) --> (EX x. P(x)) & (EX x. Q(x))"; by tac; result(); writeln"Basic test of quantifier reasoning"; (*TRUE*) Goal "?p : (EX y. ALL x. Q(x,y)) --> (ALL x. EX y. Q(x,y))"; by tac; result(); Goal "?p : (ALL x. Q(x)) --> (EX x. Q(x))"; by tac; result(); writeln"The following should fail, as they are false!"; Goal "?p : (ALL x. EX y. Q(x,y)) --> (EX y. ALL x. Q(x,y))"; by tac handle ERROR => writeln"Failed, as expected"; (*Check that subgoals remain: proof failed.*) getgoal 1; Goal "?p : (EX x. Q(x)) --> (ALL x. Q(x))"; by tac handle ERROR => writeln"Failed, as expected"; getgoal 1; Goal "?p : P(?a) --> (ALL x. P(x))"; by tac handle ERROR => writeln"Failed, as expected"; (*Check that subgoals remain: proof failed.*) getgoal 1; Goal "?p : (P(?a) --> (ALL x. Q(x))) --> (ALL x. P(x) --> Q(x))"; by tac handle ERROR => writeln"Failed, as expected"; getgoal 1; writeln"Back to things that are provable..."; Goal "?p : (ALL x. P(x)-->Q(x)) & (EX x. P(x)) --> (EX x. Q(x))"; by tac; result(); (*An example of why exI should be delayed as long as possible*) Goal "?p : (P --> (EX x. Q(x))) & P --> (EX x. Q(x))"; by tac; result(); Goal "?p : (ALL x. P(x)-->Q(f(x))) & (ALL x. Q(x)-->R(g(x))) & P(d) --> R(?a)"; by tac; (*Verify that no subgoals remain.*) uresult(); Goal "?p : (ALL x. Q(x)) --> (EX x. Q(x))"; by tac; result(); writeln"Some slow ones"; (*Principia Mathematica *11.53 *) Goal "?p : (ALL x y. P(x) --> Q(y)) <-> ((EX x. P(x)) --> (ALL y. Q(y)))"; by tac; result(); (*6 secs*) (*Principia Mathematica *11.55 *) Goal "?p : (EX x y. P(x) & Q(x,y)) <-> (EX x. P(x) & (EX y. Q(x,y)))"; by tac; result(); (*9 secs*) (*Principia Mathematica *11.61 *) Goal "?p : (EX y. ALL x. P(x) --> Q(x,y)) --> (ALL x. P(x) --> (EX y. Q(x,y)))"; by tac; result(); (*3 secs*) writeln"Reached end of file.";