src/Sequents/Modal/Tthms.ML
changeset 21426 87ac12bed1ab
parent 21425 c11ab38b78a7
child 21427 7c8f4a331f9b
equal deleted inserted replaced
21425:c11ab38b78a7 21426:87ac12bed1ab
     1 (*  Title:      91/Modal/ex/Tthms
       
     2     ID:         $Id$
       
     3     Author:     Martin Coen
       
     4     Copyright   1991  University of Cambridge
       
     5 *)
       
     6 
       
     7 (* Theorems of system T from Hughes and Cresswell and Hailpern, LNCS 129 *)
       
     8 
       
     9 try "|- []P --> P";
       
    10 try "|- [](P-->Q) --> ([]P-->[]Q)";    (* normality*)
       
    11 try "|- (P--<Q) --> []P --> []Q";
       
    12 try "|- P --> <>P";
       
    13 
       
    14 try "|-  [](P & Q) <-> []P & []Q";
       
    15 try "|-  <>(P | Q) <-> <>P | <>Q";
       
    16 try "|-  [](P<->Q) <-> (P>-<Q)";
       
    17 try "|-  <>(P-->Q) <-> ([]P--><>Q)";
       
    18 try "|-        []P <-> ~<>(~P)";
       
    19 try "|-     [](~P) <-> ~<>P";
       
    20 try "|-       ~[]P <-> <>(~P)";
       
    21 try "|-      [][]P <-> ~<><>(~P)";
       
    22 try "|- ~<>(P | Q) <-> ~<>P & ~<>Q";
       
    23 
       
    24 try "|- []P | []Q --> [](P | Q)";
       
    25 try "|- <>(P & Q) --> <>P & <>Q";
       
    26 try "|- [](P | Q) --> []P | <>Q";
       
    27 try "|- <>P & []Q --> <>(P & Q)";
       
    28 try "|- [](P | Q) --> <>P | []Q";
       
    29 try "|- <>(P-->(Q & R)) --> ([]P --> <>Q) & ([]P--><>R)";
       
    30 try "|- (P--<Q) & (Q--<R) --> (P--<R)";
       
    31 try "|- []P --> <>Q --> <>(P & Q)";