| Step |
Hyp |
Ref |
Expression |
| 1 |
|
swrdccatin2.l |
|- L = ( # ` A ) |
| 2 |
|
ccatcl |
|- ( ( A e. Word V /\ B e. Word V ) -> ( A ++ B ) e. Word V ) |
| 3 |
2
|
adantr |
|- ( ( ( A e. Word V /\ B e. Word V ) /\ ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) ) -> ( A ++ B ) e. Word V ) |
| 4 |
|
elfz0fzfz0 |
|- ( ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) -> M e. ( 0 ... N ) ) |
| 5 |
4
|
adantl |
|- ( ( ( A e. Word V /\ B e. Word V ) /\ ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) ) -> M e. ( 0 ... N ) ) |
| 6 |
|
elfzuz2 |
|- ( M e. ( 0 ... L ) -> L e. ( ZZ>= ` 0 ) ) |
| 7 |
|
fzss1 |
|- ( L e. ( ZZ>= ` 0 ) -> ( L ... ( L + ( # ` B ) ) ) C_ ( 0 ... ( L + ( # ` B ) ) ) ) |
| 8 |
6 7
|
syl |
|- ( M e. ( 0 ... L ) -> ( L ... ( L + ( # ` B ) ) ) C_ ( 0 ... ( L + ( # ` B ) ) ) ) |
| 9 |
8
|
sselda |
|- ( ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) -> N e. ( 0 ... ( L + ( # ` B ) ) ) ) |
| 10 |
|
ccatlen |
|- ( ( A e. Word V /\ B e. Word V ) -> ( # ` ( A ++ B ) ) = ( ( # ` A ) + ( # ` B ) ) ) |
| 11 |
1
|
oveq1i |
|- ( L + ( # ` B ) ) = ( ( # ` A ) + ( # ` B ) ) |
| 12 |
10 11
|
eqtr4di |
|- ( ( A e. Word V /\ B e. Word V ) -> ( # ` ( A ++ B ) ) = ( L + ( # ` B ) ) ) |
| 13 |
12
|
oveq2d |
|- ( ( A e. Word V /\ B e. Word V ) -> ( 0 ... ( # ` ( A ++ B ) ) ) = ( 0 ... ( L + ( # ` B ) ) ) ) |
| 14 |
13
|
eleq2d |
|- ( ( A e. Word V /\ B e. Word V ) -> ( N e. ( 0 ... ( # ` ( A ++ B ) ) ) <-> N e. ( 0 ... ( L + ( # ` B ) ) ) ) ) |
| 15 |
9 14
|
imbitrrid |
|- ( ( A e. Word V /\ B e. Word V ) -> ( ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) -> N e. ( 0 ... ( # ` ( A ++ B ) ) ) ) ) |
| 16 |
15
|
imp |
|- ( ( ( A e. Word V /\ B e. Word V ) /\ ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) ) -> N e. ( 0 ... ( # ` ( A ++ B ) ) ) ) |
| 17 |
3 5 16
|
3jca |
|- ( ( ( A e. Word V /\ B e. Word V ) /\ ( M e. ( 0 ... L ) /\ N e. ( L ... ( L + ( # ` B ) ) ) ) ) -> ( ( A ++ B ) e. Word V /\ M e. ( 0 ... N ) /\ N e. ( 0 ... ( # ` ( A ++ B ) ) ) ) ) |