Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Richard Penner
Exploring Topology via Seifert and Threlfall
Equinumerosity of sets of relations and maps
fsovcnvd
Metamath Proof Explorer
Description: The value of the converse ( A O B ) is ( B O A ) , where
O is the operator which maps between maps from one base set to
subsets of the second to maps from the second base set to subsets
of the first for base sets, gives a family of functions that
include their own inverse. (Contributed by RP , 27-Apr-2021)
Ref
Expression
Hypotheses
fsovd.fs
⊢ 𝑂 = ( 𝑎 ∈ V , 𝑏 ∈ V ↦ ( 𝑓 ∈ ( 𝒫 𝑏 ↑m 𝑎 ) ↦ ( 𝑦 ∈ 𝑏 ↦ { 𝑥 ∈ 𝑎 ∣ 𝑦 ∈ ( 𝑓 ‘ 𝑥 ) } ) ) )
fsovd.a
⊢ ( 𝜑 → 𝐴 ∈ 𝑉 )
fsovd.b
⊢ ( 𝜑 → 𝐵 ∈ 𝑊 )
fsovfvd.g
⊢ 𝐺 = ( 𝐴 𝑂 𝐵 )
fsovcnvlem.h
⊢ 𝐻 = ( 𝐵 𝑂 𝐴 )
Assertion
fsovcnvd
⊢ ( 𝜑 → ◡ 𝐺 = 𝐻 )
Proof
Step
Hyp
Ref
Expression
1
fsovd.fs
⊢ 𝑂 = ( 𝑎 ∈ V , 𝑏 ∈ V ↦ ( 𝑓 ∈ ( 𝒫 𝑏 ↑m 𝑎 ) ↦ ( 𝑦 ∈ 𝑏 ↦ { 𝑥 ∈ 𝑎 ∣ 𝑦 ∈ ( 𝑓 ‘ 𝑥 ) } ) ) )
2
fsovd.a
⊢ ( 𝜑 → 𝐴 ∈ 𝑉 )
3
fsovd.b
⊢ ( 𝜑 → 𝐵 ∈ 𝑊 )
4
fsovfvd.g
⊢ 𝐺 = ( 𝐴 𝑂 𝐵 )
5
fsovcnvlem.h
⊢ 𝐻 = ( 𝐵 𝑂 𝐴 )
6
1 2 3 4
fsovfd
⊢ ( 𝜑 → 𝐺 : ( 𝒫 𝐵 ↑m 𝐴 ) ⟶ ( 𝒫 𝐴 ↑m 𝐵 ) )
7
1 3 2 5
fsovfd
⊢ ( 𝜑 → 𝐻 : ( 𝒫 𝐴 ↑m 𝐵 ) ⟶ ( 𝒫 𝐵 ↑m 𝐴 ) )
8
1 2 3 4 5
fsovcnvlem
⊢ ( 𝜑 → ( 𝐻 ∘ 𝐺 ) = ( I ↾ ( 𝒫 𝐵 ↑m 𝐴 ) ) )
9
1 3 2 5 4
fsovcnvlem
⊢ ( 𝜑 → ( 𝐺 ∘ 𝐻 ) = ( I ↾ ( 𝒫 𝐴 ↑m 𝐵 ) ) )
10
6 7 8 9
2fcoidinvd
⊢ ( 𝜑 → ◡ 𝐺 = 𝐻 )