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src/Sequents/LK/prop.ML

author | wenzelm |

Tue, 30 May 2000 16:08:38 +0200 | |

changeset 9000 | c20d58286a51 |

parent 6252 | 935f183bf406 |

child 17481 | 75166ebb619b |

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

cleaned up;

(* Title: LK/ex/prop ID: $Id$ Author: Lawrence C Paulson, Cambridge University Computer Laboratory Copyright 1992 University of Cambridge Classical sequent calculus: examples with propositional connectives Can be read to test the LK system. *) writeln"LK/ex/prop: propositional examples"; writeln"absorptive laws of & and | "; goal LK.thy "|- P & P <-> P"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- P | P <-> P"; by (fast_tac prop_pack 1); result(); writeln"commutative laws of & and | "; goal LK.thy "|- P & Q <-> Q & P"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- P | Q <-> Q | P"; by (fast_tac prop_pack 1); result(); writeln"associative laws of & and | "; goal LK.thy "|- (P & Q) & R <-> P & (Q & R)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P | Q) | R <-> P | (Q | R)"; by (fast_tac prop_pack 1); result(); writeln"distributive laws of & and | "; goal LK.thy "|- (P & Q) | R <-> (P | R) & (Q | R)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P | Q) & R <-> (P & R) | (Q & R)"; by (fast_tac prop_pack 1); result(); writeln"Laws involving implication"; goal LK.thy "|- (P|Q --> R) <-> (P-->R) & (Q-->R)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P & Q --> R) <-> (P--> (Q-->R))"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P --> Q & R) <-> (P-->Q) & (P-->R)"; by (fast_tac prop_pack 1); result(); writeln"Classical theorems"; goal LK.thy "|- P|Q --> P| ~P&Q"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P-->Q)&(~P-->R) --> (P&Q | R)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- P&Q | ~P&R <-> (P-->Q)&(~P-->R)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- (P-->Q) | (P-->R) <-> (P --> Q | R)"; by (fast_tac prop_pack 1); result(); (*If and only if*) goal LK.thy "|- (P<->Q) <-> (Q<->P)"; by (fast_tac prop_pack 1); result(); goal LK.thy "|- ~ (P <-> ~P)"; by (fast_tac prop_pack 1); result(); (*Sample problems from F. J. Pelletier, Seventy-Five Problems for Testing Automatic Theorem Provers, J. Automated Reasoning 2 (1986), 191-216. Errata, JAR 4 (1988), 236-236. *) (*1*) goal LK.thy "|- (P-->Q) <-> (~Q --> ~P)"; by (fast_tac prop_pack 1); result(); (*2*) goal LK.thy "|- ~ ~ P <-> P"; by (fast_tac prop_pack 1); result(); (*3*) goal LK.thy "|- ~(P-->Q) --> (Q-->P)"; by (fast_tac prop_pack 1); result(); (*4*) goal LK.thy "|- (~P-->Q) <-> (~Q --> P)"; by (fast_tac prop_pack 1); result(); (*5*) goal LK.thy "|- ((P|Q)-->(P|R)) --> (P|(Q-->R))"; by (fast_tac prop_pack 1); result(); (*6*) goal LK.thy "|- P | ~ P"; by (fast_tac prop_pack 1); result(); (*7*) goal LK.thy "|- P | ~ ~ ~ P"; by (fast_tac prop_pack 1); result(); (*8. Peirce's law*) goal LK.thy "|- ((P-->Q) --> P) --> P"; by (fast_tac prop_pack 1); result(); (*9*) goal LK.thy "|- ((P|Q) & (~P|Q) & (P| ~Q)) --> ~ (~P | ~Q)"; by (fast_tac prop_pack 1); result(); (*10*) goal LK.thy "Q-->R, R-->P&Q, P-->(Q|R) |- P<->Q"; by (fast_tac prop_pack 1); result(); (*11. Proved in each direction (incorrectly, says Pelletier!!) *) goal LK.thy "|- P<->P"; by (fast_tac prop_pack 1); result(); (*12. "Dijkstra's law"*) goal LK.thy "|- ((P <-> Q) <-> R) <-> (P <-> (Q <-> R))"; by (fast_tac prop_pack 1); result(); (*13. Distributive law*) goal LK.thy "|- P | (Q & R) <-> (P | Q) & (P | R)"; by (fast_tac prop_pack 1); result(); (*14*) goal LK.thy "|- (P <-> Q) <-> ((Q | ~P) & (~Q|P))"; by (fast_tac prop_pack 1); result(); (*15*) goal LK.thy "|- (P --> Q) <-> (~P | Q)"; by (fast_tac prop_pack 1); result(); (*16*) goal LK.thy "|- (P-->Q) | (Q-->P)"; by (fast_tac prop_pack 1); result(); (*17*) goal LK.thy "|- ((P & (Q-->R))-->S) <-> ((~P | Q | S) & (~P | ~R | S))"; by (fast_tac prop_pack 1); result(); writeln"Reached end of file.";