Metamath Proof Explorer


Theorem ccats1val1

Description: Value of a symbol in the left half of a word concatenated with a single symbol. (Contributed by Alexander van der Vekens, 5-Aug-2018) (Revised by JJ, 20-Jan-2024)

Ref Expression
Assertion ccats1val1
|- ( ( W e. Word V /\ I e. ( 0 ..^ ( # ` W ) ) ) -> ( ( W ++ <" S "> ) ` I ) = ( W ` I ) )

Proof

Step Hyp Ref Expression
1 s1cli
 |-  <" S "> e. Word _V
2 ccatval1
 |-  ( ( W e. Word V /\ <" S "> e. Word _V /\ I e. ( 0 ..^ ( # ` W ) ) ) -> ( ( W ++ <" S "> ) ` I ) = ( W ` I ) )
3 1 2 mp3an2
 |-  ( ( W e. Word V /\ I e. ( 0 ..^ ( # ` W ) ) ) -> ( ( W ++ <" S "> ) ` I ) = ( W ` I ) )