| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ackbij.f |  |-  F = ( x e. ( ~P _om i^i Fin ) |-> ( card ` U_ y e. x ( { y } X. ~P y ) ) ) | 
						
							| 2 | 1 | ackbij1lem10 |  |-  F : ( ~P _om i^i Fin ) --> _om | 
						
							| 3 | 1 | ackbij1lem11 |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> A e. ( ~P _om i^i Fin ) ) | 
						
							| 4 |  | ffvelcdm |  |-  ( ( F : ( ~P _om i^i Fin ) --> _om /\ A e. ( ~P _om i^i Fin ) ) -> ( F ` A ) e. _om ) | 
						
							| 5 | 2 3 4 | sylancr |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` A ) e. _om ) | 
						
							| 6 |  | difssd |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( B \ A ) C_ B ) | 
						
							| 7 | 1 | ackbij1lem11 |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ ( B \ A ) C_ B ) -> ( B \ A ) e. ( ~P _om i^i Fin ) ) | 
						
							| 8 | 6 7 | syldan |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( B \ A ) e. ( ~P _om i^i Fin ) ) | 
						
							| 9 |  | ffvelcdm |  |-  ( ( F : ( ~P _om i^i Fin ) --> _om /\ ( B \ A ) e. ( ~P _om i^i Fin ) ) -> ( F ` ( B \ A ) ) e. _om ) | 
						
							| 10 | 2 8 9 | sylancr |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` ( B \ A ) ) e. _om ) | 
						
							| 11 |  | nnaword1 |  |-  ( ( ( F ` A ) e. _om /\ ( F ` ( B \ A ) ) e. _om ) -> ( F ` A ) C_ ( ( F ` A ) +o ( F ` ( B \ A ) ) ) ) | 
						
							| 12 | 5 10 11 | syl2anc |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` A ) C_ ( ( F ` A ) +o ( F ` ( B \ A ) ) ) ) | 
						
							| 13 |  | disjdif |  |-  ( A i^i ( B \ A ) ) = (/) | 
						
							| 14 | 13 | a1i |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( A i^i ( B \ A ) ) = (/) ) | 
						
							| 15 | 1 | ackbij1lem9 |  |-  ( ( A e. ( ~P _om i^i Fin ) /\ ( B \ A ) e. ( ~P _om i^i Fin ) /\ ( A i^i ( B \ A ) ) = (/) ) -> ( F ` ( A u. ( B \ A ) ) ) = ( ( F ` A ) +o ( F ` ( B \ A ) ) ) ) | 
						
							| 16 | 3 8 14 15 | syl3anc |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` ( A u. ( B \ A ) ) ) = ( ( F ` A ) +o ( F ` ( B \ A ) ) ) ) | 
						
							| 17 |  | undif |  |-  ( A C_ B <-> ( A u. ( B \ A ) ) = B ) | 
						
							| 18 | 17 | biimpi |  |-  ( A C_ B -> ( A u. ( B \ A ) ) = B ) | 
						
							| 19 | 18 | adantl |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( A u. ( B \ A ) ) = B ) | 
						
							| 20 | 19 | fveq2d |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` ( A u. ( B \ A ) ) ) = ( F ` B ) ) | 
						
							| 21 | 16 20 | eqtr3d |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( ( F ` A ) +o ( F ` ( B \ A ) ) ) = ( F ` B ) ) | 
						
							| 22 | 12 21 | sseqtrd |  |-  ( ( B e. ( ~P _om i^i Fin ) /\ A C_ B ) -> ( F ` A ) C_ ( F ` B ) ) |