--- /dev/null
+include "logic/equality.ma".
+
+(* Inclusion of: COL002-5.p *)
+
+(* -------------------------------------------------------------------------- *)
+
+(* File : COL002-5 : TPTP v3.2.0. Bugfixed v3.1.0. *)
+
+(* Domain : Combinatory Logic *)
+
+(* Problem : Weak fixed point for S, B, C, and I *)
+
+(* Version : [WM88] (equality) axioms. *)
+
+(* Theorem formulation : The fixed point is provided and checked. *)
+
+(* English : The weak fixed point property holds for the set P consisting *)
+
+(* of the combinators S, B, C, and I, where ((Sx)y)z = (xz)(yz), *)
+
+(* ((Bx)y)z = x(yz), ((Cx)y)z = (xz)y, and Ix = x. *)
+
+(* Refs : [WM88] Wos & McCune (1988), Challenge Problems Focusing on Eq *)
+
+(* Source : [TPTP] *)
+
+(* Names : *)
+
+(* Status : Unsatisfiable *)
+
+(* Rating : 0.43 v3.1.0 *)
+
+(* Syntax : Number of clauses : 6 ( 0 non-Horn; 6 unit; 1 RR) *)
+
+(* Number of atoms : 6 ( 6 equality) *)
+
+(* Maximal clause size : 1 ( 1 average) *)
+
+(* Number of predicates : 1 ( 0 propositional; 2-2 arity) *)
+
+(* Number of functors : 7 ( 5 constant; 0-2 arity) *)
+
+(* Number of variables : 11 ( 0 singleton) *)
+
+(* Maximal term depth : 6 ( 3 average) *)
+
+(* Comments : This is the one found in proof 3 of C1.1 in [WM88]. *)
+
+(* Bugfixes : Fixed clauses weak_fixed_point and prove_weak_fixed_point. *)
+
+(* -------------------------------------------------------------------------- *)
+ntheorem prove_weak_fixed_point:
+ ∀Univ:Type.∀X:Univ.∀Y:Univ.∀Z:Univ.
+∀apply:∀_:Univ.∀_:Univ.Univ.
+∀b:Univ.
+∀c:Univ.
+∀fixed_pt:Univ.
+∀i:Univ.
+∀s:Univ.
+∀weak_fixed_point:∀_:Univ.Univ.
+∀H0:∀X:Univ.eq Univ (weak_fixed_point X) (apply (apply (apply s (apply c (apply b X))) (apply s (apply c (apply b X)))) (apply s (apply c (apply b X)))).
+∀H1:∀X:Univ.eq Univ (apply i X) X.
+∀H2:∀X:Univ.∀Y:Univ.∀Z:Univ.eq Univ (apply (apply (apply c X) Y) Z) (apply (apply X Z) Y).
+∀H3:∀X:Univ.∀Y:Univ.∀Z:Univ.eq Univ (apply (apply (apply b X) Y) Z) (apply X (apply Y Z)).
+∀H4:∀X:Univ.∀Y:Univ.∀Z:Univ.eq Univ (apply (apply (apply s X) Y) Z) (apply (apply X Z) (apply Y Z)).eq Univ (weak_fixed_point fixed_pt) (apply fixed_pt (weak_fixed_point fixed_pt))
+.
+#Univ.
+#X.
+#Y.
+#Z.
+#apply.
+#b.
+#c.
+#fixed_pt.
+#i.
+#s.
+#weak_fixed_point.
+#H0.
+#H1.
+#H2.
+#H3.
+#H4.
+nauto by H0,H1,H2,H3,H4;
+nqed.
+
+(* -------------------------------------------------------------------------- *)