--- /dev/null
+include "logic/equality.ma".
+
+(* Inclusion of: COL017-1.p *)
+
+(* -------------------------------------------------------------------------- *)
+
+(* File : COL017-1 : TPTP v3.2.0. Released v1.0.0. *)
+
+(* Domain : Combinatory Logic *)
+
+(* Problem : Weak fixed point for B, M, and T *)
+
+(* Version : [WM88] (equality) axioms. *)
+
+(* English : The weak fixed point property holds for the set P consisting *)
+
+(* of the combinators B, M, and T, where ((Bx)y)z = x(yz), *)
+
+(* Mx = xx, (Tx)y = yx. *)
+
+(* Refs : [Smu85] Smullyan (1978), To Mock a Mocking Bird and Other Logi *)
+
+(* : [MW87] McCune & Wos (1987), A Case Study in Automated Theorem *)
+
+(* : [WM88] Wos & McCune (1988), Challenge Problems Focusing on Eq *)
+
+(* : [MW88] McCune & Wos (1988), Some Fixed Point Problems in Comb *)
+
+(* Source : [MW88] *)
+
+(* Names : - [MW88] *)
+
+(* Status : Unsatisfiable *)
+
+(* Rating : 0.00 v2.0.0 *)
+
+(* Syntax : Number of clauses : 4 ( 0 non-Horn; 4 unit; 1 RR) *)
+
+(* Number of atoms : 4 ( 4 equality) *)
+
+(* Maximal clause size : 1 ( 1 average) *)
+
+(* Number of predicates : 1 ( 0 propositional; 2-2 arity) *)
+
+(* Number of functors : 5 ( 4 constant; 0-2 arity) *)
+
+(* Number of variables : 7 ( 0 singleton) *)
+
+(* Maximal term depth : 4 ( 2 average) *)
+
+(* Comments : *)
+
+(* -------------------------------------------------------------------------- *)
+ntheorem prove_fixed_point:
+ ∀Univ:Type.∀X:Univ.∀Y:Univ.∀Z:Univ.
+∀apply:∀_:Univ.∀_:Univ.Univ.
+∀b:Univ.
+∀combinator:Univ.
+∀m:Univ.
+∀t:Univ.
+∀H0:∀X:Univ.∀Y:Univ.eq Univ (apply (apply t X) Y) (apply Y X).
+∀H1:∀X:Univ.eq Univ (apply m X) (apply X X).
+∀H2:∀X:Univ.∀Y:Univ.∀Z:Univ.eq Univ (apply (apply (apply b X) Y) Z) (apply X (apply Y Z)).∃Y:Univ.eq Univ Y (apply combinator Y)
+.
+#Univ.
+#X.
+#Y.
+#Z.
+#apply.
+#b.
+#combinator.
+#m.
+#t.
+#H0.
+#H1.
+#H2.
+napply ex_intro[
+nid2:
+nauto by H0,H1,H2;
+nid|
+skip]
+nqed.
+
+(* -------------------------------------------------------------------------- *)