Theorem dihcnvid1

Description: The converse isomorphism of an isomorphism. (Contributed by NM, 5-Aug-2014)

	Ref	Expression
Hypotheses	dihcnvid1.b	⊢ 𝐵 = ( Base ‘ 𝐾 )
	dihcnvid1.h	⊢ 𝐻 = ( LHyp ‘ 𝐾 )
	dihcnvid1.i	⊢ 𝐼 = ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 )
Assertion	dihcnvid1	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑊 ∈ 𝐻 ) ∧ 𝑋 ∈ 𝐵 ) → ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) ) = 𝑋 )

Proof

Step	Hyp	Ref	Expression
1		dihcnvid1.b	⊢ 𝐵 = ( Base ‘ 𝐾 )
2		dihcnvid1.h	⊢ 𝐻 = ( LHyp ‘ 𝐾 )
3		dihcnvid1.i	⊢ 𝐼 = ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 )
4		eqid	⊢ ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) = ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 )
5		eqid	⊢ ( LSubSp ‘ ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) ) = ( LSubSp ‘ ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) )
6	1 2 3 4 5	dihf11	⊢ ( ( 𝐾 ∈ HL ∧ 𝑊 ∈ 𝐻 ) → 𝐼 : 𝐵 –1-1→ ( LSubSp ‘ ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) ) )
7		f1f1orn	⊢ ( 𝐼 : 𝐵 –1-1→ ( LSubSp ‘ ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) ) → 𝐼 : 𝐵 –1-1-onto→ ran 𝐼 )
8	6 7	syl	⊢ ( ( 𝐾 ∈ HL ∧ 𝑊 ∈ 𝐻 ) → 𝐼 : 𝐵 –1-1-onto→ ran 𝐼 )
9		f1ocnvfv1	⊢ ( ( 𝐼 : 𝐵 –1-1-onto→ ran 𝐼 ∧ 𝑋 ∈ 𝐵 ) → ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) ) = 𝑋 )
10	8 9	sylan	⊢ ( ( ( 𝐾 ∈ HL ∧ 𝑊 ∈ 𝐻 ) ∧ 𝑋 ∈ 𝐵 ) → ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) ) = 𝑋 )