Metamath Proof Explorer


Theorem evpmval

Description: Value of the set of even permutations, the alternating group. (Contributed by Thierry Arnoux, 1-Nov-2023)

Ref Expression
Hypothesis evpmval.1 𝐴 = ( pmEven ‘ 𝐷 )
Assertion evpmval ( 𝐷𝑉𝐴 = ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) )

Proof

Step Hyp Ref Expression
1 evpmval.1 𝐴 = ( pmEven ‘ 𝐷 )
2 elex ( 𝐷𝑉𝐷 ∈ V )
3 fveq2 ( 𝑑 = 𝐷 → ( pmSgn ‘ 𝑑 ) = ( pmSgn ‘ 𝐷 ) )
4 3 cnveqd ( 𝑑 = 𝐷 ( pmSgn ‘ 𝑑 ) = ( pmSgn ‘ 𝐷 ) )
5 4 imaeq1d ( 𝑑 = 𝐷 → ( ( pmSgn ‘ 𝑑 ) “ { 1 } ) = ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) )
6 df-evpm pmEven = ( 𝑑 ∈ V ↦ ( ( pmSgn ‘ 𝑑 ) “ { 1 } ) )
7 fvex ( pmSgn ‘ 𝐷 ) ∈ V
8 7 cnvex ( pmSgn ‘ 𝐷 ) ∈ V
9 8 imaex ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) ∈ V
10 5 6 9 fvmpt ( 𝐷 ∈ V → ( pmEven ‘ 𝐷 ) = ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) )
11 2 10 syl ( 𝐷𝑉 → ( pmEven ‘ 𝐷 ) = ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) )
12 1 11 syl5eq ( 𝐷𝑉𝐴 = ( ( pmSgn ‘ 𝐷 ) “ { 1 } ) )