Metamath Proof Explorer


Theorem pcovalg

Description: Evaluate the concatenation of two paths. (Contributed by Mario Carneiro, 7-Jun-2014)

Ref Expression
Hypotheses pcoval.2
|- ( ph -> F e. ( II Cn J ) )
pcoval.3
|- ( ph -> G e. ( II Cn J ) )
Assertion pcovalg
|- ( ( ph /\ X e. ( 0 [,] 1 ) ) -> ( ( F ( *p ` J ) G ) ` X ) = if ( X <_ ( 1 / 2 ) , ( F ` ( 2 x. X ) ) , ( G ` ( ( 2 x. X ) - 1 ) ) ) )

Proof

Step Hyp Ref Expression
1 pcoval.2
 |-  ( ph -> F e. ( II Cn J ) )
2 pcoval.3
 |-  ( ph -> G e. ( II Cn J ) )
3 1 2 pcoval
 |-  ( ph -> ( F ( *p ` J ) G ) = ( x e. ( 0 [,] 1 ) |-> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) ) )
4 3 fveq1d
 |-  ( ph -> ( ( F ( *p ` J ) G ) ` X ) = ( ( x e. ( 0 [,] 1 ) |-> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) ) ` X ) )
5 breq1
 |-  ( x = X -> ( x <_ ( 1 / 2 ) <-> X <_ ( 1 / 2 ) ) )
6 oveq2
 |-  ( x = X -> ( 2 x. x ) = ( 2 x. X ) )
7 6 fveq2d
 |-  ( x = X -> ( F ` ( 2 x. x ) ) = ( F ` ( 2 x. X ) ) )
8 6 fvoveq1d
 |-  ( x = X -> ( G ` ( ( 2 x. x ) - 1 ) ) = ( G ` ( ( 2 x. X ) - 1 ) ) )
9 5 7 8 ifbieq12d
 |-  ( x = X -> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) = if ( X <_ ( 1 / 2 ) , ( F ` ( 2 x. X ) ) , ( G ` ( ( 2 x. X ) - 1 ) ) ) )
10 eqid
 |-  ( x e. ( 0 [,] 1 ) |-> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) ) = ( x e. ( 0 [,] 1 ) |-> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) )
11 fvex
 |-  ( F ` ( 2 x. X ) ) e. _V
12 fvex
 |-  ( G ` ( ( 2 x. X ) - 1 ) ) e. _V
13 11 12 ifex
 |-  if ( X <_ ( 1 / 2 ) , ( F ` ( 2 x. X ) ) , ( G ` ( ( 2 x. X ) - 1 ) ) ) e. _V
14 9 10 13 fvmpt
 |-  ( X e. ( 0 [,] 1 ) -> ( ( x e. ( 0 [,] 1 ) |-> if ( x <_ ( 1 / 2 ) , ( F ` ( 2 x. x ) ) , ( G ` ( ( 2 x. x ) - 1 ) ) ) ) ` X ) = if ( X <_ ( 1 / 2 ) , ( F ` ( 2 x. X ) ) , ( G ` ( ( 2 x. X ) - 1 ) ) ) )
15 4 14 sylan9eq
 |-  ( ( ph /\ X e. ( 0 [,] 1 ) ) -> ( ( F ( *p ` J ) G ) ` X ) = if ( X <_ ( 1 / 2 ) , ( F ` ( 2 x. X ) ) , ( G ` ( ( 2 x. X ) - 1 ) ) ) )