1 include "logic/equality.ma".
3 (* Inclusion of: GRP001-4.p *)
5 (* -------------------------------------------------------------------------- *)
7 (* File : GRP001-4 : TPTP v3.7.0. Released v1.0.0. *)
9 (* Domain : Group Theory *)
11 (* Problem : X^2 = identity => commutativity *)
13 (* Version : [Wos65] (equality) axioms : Incomplete. *)
15 (* English : If the square of every element is the identity, the system *)
19 (* Refs : [Wos65] Wos (1965), Unpublished Note *)
21 (* : [Pel86] Pelletier (1986), Seventy-five Problems for Testing Au *)
23 (* Source : [Pel86] *)
25 (* Names : Pelletier 65 [Pel86] *)
27 (* : x2_quant.in [OTTER] *)
29 (* Status : Unsatisfiable *)
31 (* Rating : 0.00 v2.2.1, 0.22 v2.2.0, 0.29 v2.1.0, 0.25 v2.0.0 *)
33 (* Syntax : Number of clauses : 5 ( 0 non-Horn; 5 unit; 2 RR) *)
35 (* Number of atoms : 5 ( 5 equality) *)
37 (* Maximal clause size : 1 ( 1 average) *)
39 (* Number of predicates : 1 ( 0 propositional; 2-2 arity) *)
41 (* Number of functors : 5 ( 4 constant; 0-2 arity) *)
43 (* Number of variables : 5 ( 0 singleton) *)
45 (* Maximal term depth : 3 ( 2 average) *)
47 (* Comments : [Pel86] says "... problems, published I think, by Larry Wos *)
49 (* (but I cannot locate where)." *)
51 (* -------------------------------------------------------------------------- *)
53 (* ----The operation '*' is associative *)
55 (* ----There exists an identity element 'e' defined below. *)
56 ntheorem prove_b_times_a_is_c:
57 (∀Univ:Type.∀X:Univ.∀Y:Univ.∀Z:Univ.
62 ∀multiply:∀_:Univ.∀_:Univ.Univ.
63 ∀H0:eq Univ (multiply a b) c.
64 ∀H1:∀X:Univ.eq Univ (multiply X X) identity.
65 ∀H2:∀X:Univ.eq Univ (multiply identity X) X.
66 ∀H3:∀X:Univ.∀Y:Univ.∀Z:Univ.eq Univ (multiply (multiply X Y) Z) (multiply X (multiply Y Z)).eq Univ (multiply b a) c)
81 nauto by H0,H1,H2,H3 ##;
82 ntry (nassumption) ##;
85 (* -------------------------------------------------------------------------- *)