Proof 01. 1 ⊢ set x, hypo. 02. 2 ⊢ set y, hypo. 03. ⊢ set ∅, empty_set_is_set. 04. ⊢ set {∅}, set_sg 3. 05. ⊢ img {(∅, x), ({∅}, y)} {∅, {∅}} = img {(∅, x)} {∅, {∅}} ∪ img {({∅}, y)} {∅, {∅}}, img_union. 06. ⊢ img {(∅, x)} {∅, {∅}} = img {(∅, x)} {∅} ∪ img {(∅, x)} {{∅}}, img_dist_union. 07. ⊢ img {({∅}, y)} {∅, {∅}} = img {({∅}, y)} {∅} ∪ img {({∅}, y)} {{∅}}, img_dist_union. 08. 1 ⊢ img {(∅, x)} {∅} = {x}, img_sg_sg 3 1. 09. 2 ⊢ img {({∅}, y)} {{∅}} = {y}, img_sg_sg 4 2. 10. ⊢ ¬∅ = {∅}, zero_neq_one. 11. ⊢ ¬{∅} = ∅, neq_symm 10. 12. 1 ⊢ img {(∅, x)} {{∅}} = ∅, img_sg_sg_neq 3 1 4 10. 13. 2 ⊢ img {({∅}, y)} {∅} = ∅, img_sg_sg_neq 4 2 3 11. 14. 1 ⊢ img {(∅, x)} {∅, {∅}} = {x} ∪ img {(∅, x)} {{∅}}, eq_subst 8 6, P t ↔ img {(∅, x)} {∅, {∅}} = t ∪ img {(∅, x)} {{∅}}. 15. 1 ⊢ img {(∅, x)} {∅, {∅}} = {x} ∪ ∅, eq_subst 12 14, P t ↔ img {(∅, x)} {∅, {∅}} = {x} ∪ t. 16. ⊢ {x} ∪ ∅ = {x}, union_neutr. 17. 1 ⊢ img {(∅, x)} {∅, {∅}} = {x}, eq_subst 16 15, P t ↔ img {(∅, x)} {∅, {∅}} = t. 18. 2 ⊢ img {({∅}, y)} {∅, {∅}} = ∅ ∪ img {({∅}, y)} {{∅}}, eq_subst 13 7, P t ↔ img {({∅}, y)} {∅, {∅}} = t ∪ img {({∅}, y)} {{∅}}. 19. 2 ⊢ img {({∅}, y)} {∅, {∅}} = ∅ ∪ {y}, eq_subst 9 18, P t ↔ img {({∅}, y)} {∅, {∅}} = ∅ ∪ t. 21. ⊢ ∅ ∪ {y} = {y}, union_neutl. 22. 2 ⊢ img {({∅}, y)} {∅, {∅}} = {y}, eq_subst 21 19, P t ↔ img {({∅}, y)} {∅, {∅}} = t. 23. 1 ⊢ img {(∅, x), ({∅}, y)} {∅, {∅}} = {x} ∪ img {({∅}, y)} {∅, {∅}}, eq_subst 17 5, P t ↔ img {(∅, x), ({∅}, y)} {∅, {∅}} = t ∪ img {({∅}, y)} {∅, {∅}}. 24. 1, 2 ⊢ img {(∅, x), ({∅}, y)} {∅, {∅}} = {x} ∪ {y}, eq_subst 22 23, P t ↔ img {(∅, x), ({∅}, y)} {∅, {∅}} = {x} ∪ t. img_graph2. ⊢ set x → set y → img {(∅, x), ({∅}, y)} {∅, {∅}} = {x, y}, subj_intro_ii 24.
Dependencies
The given proof depends on 10 axioms:
comp, efq, eq_refl, eq_subst, ext, infinity, lem, pairing, subset, union.