% Mizar problem: t6_gtarski4,gtarski4,161,7 
fof(t6_gtarski4, conjecture,  (! [A] :  (l1_gtarski1(A) =>  (! [B] :  (m1_subset_1(B, u1_struct_0(A)) =>  (! [C] :  (m1_subset_1(C, u1_struct_0(A)) =>  (! [D] :  (m1_subset_1(D, u1_struct_0(A)) =>  ( (r9_gtarski3(A, B, D, C) | r1_gtarski1(A, B, C, D))  => r6_gtarski1(A, B, C, D)) ) ) ) ) ) ) ) ) ).
fof(d12_gtarski3, axiom,  (! [A] :  (l1_gtarski1(A) =>  (! [B] :  (m1_subset_1(B, u1_struct_0(A)) =>  (! [C] :  (m1_subset_1(C, u1_struct_0(A)) =>  (! [D] :  (m1_subset_1(D, u1_struct_0(A)) =>  (r9_gtarski3(A, B, C, D) <=>  (r1_gtarski1(A, B, D, C) & r2_gtarski1(A, D, B, D, C)) ) ) ) ) ) ) ) ) ) ).
fof(d17_gtarski1, axiom,  (! [A] :  (l1_gtarski1(A) =>  (! [B] :  (m1_subset_1(B, u1_struct_0(A)) =>  (! [C] :  (m1_subset_1(C, u1_struct_0(A)) =>  (! [D] :  (m1_subset_1(D, u1_struct_0(A)) =>  (r6_gtarski1(A, B, C, D) <=>  ~ ( ( ~ (r1_gtarski1(A, B, C, D))  &  ( ~ (r1_gtarski1(A, C, D, B))  &  ~ (r1_gtarski1(A, D, B, C)) ) ) ) ) ) ) ) ) ) ) ) ) ).
fof(dt_l1_gtarski1, axiom,  (! [A] :  (l1_gtarski1(A) => l1_struct_0(A)) ) ).
fof(dt_l1_struct_0, axiom, $true).
fof(dt_m1_subset_1, axiom, $true).
fof(dt_u1_struct_0, axiom, $true).
fof(existence_l1_gtarski1, axiom,  (? [A] : l1_gtarski1(A)) ).
fof(existence_l1_struct_0, axiom,  (? [A] : l1_struct_0(A)) ).
fof(existence_m1_subset_1, axiom,  (! [A] :  (? [B] : m1_subset_1(B, A)) ) ).
