Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Richard Penner
Exploring Topology via Seifert and Threlfall
Equinumerosity of sets of relations and maps
rfovf1od
Metamath Proof Explorer
Description: The value of the operator, ( A O B ) , which maps between
relations and functions for relations between base sets, A and
B , is a bijection. (Contributed by RP , 27-Apr-2021)
Ref
Expression
Hypotheses
rfovd.rf
⊢ 𝑂 = ( 𝑎 ∈ V , 𝑏 ∈ V ↦ ( 𝑟 ∈ 𝒫 ( 𝑎 × 𝑏 ) ↦ ( 𝑥 ∈ 𝑎 ↦ { 𝑦 ∈ 𝑏 ∣ 𝑥 𝑟 𝑦 } ) ) )
rfovd.a
⊢ ( 𝜑 → 𝐴 ∈ 𝑉 )
rfovd.b
⊢ ( 𝜑 → 𝐵 ∈ 𝑊 )
rfovcnvf1od.f
⊢ 𝐹 = ( 𝐴 𝑂 𝐵 )
Assertion
rfovf1od
⊢ ( 𝜑 → 𝐹 : 𝒫 ( 𝐴 × 𝐵 ) –1-1 -onto → ( 𝒫 𝐵 ↑m 𝐴 ) )
Proof
Step
Hyp
Ref
Expression
1
rfovd.rf
⊢ 𝑂 = ( 𝑎 ∈ V , 𝑏 ∈ V ↦ ( 𝑟 ∈ 𝒫 ( 𝑎 × 𝑏 ) ↦ ( 𝑥 ∈ 𝑎 ↦ { 𝑦 ∈ 𝑏 ∣ 𝑥 𝑟 𝑦 } ) ) )
2
rfovd.a
⊢ ( 𝜑 → 𝐴 ∈ 𝑉 )
3
rfovd.b
⊢ ( 𝜑 → 𝐵 ∈ 𝑊 )
4
rfovcnvf1od.f
⊢ 𝐹 = ( 𝐴 𝑂 𝐵 )
5
1 2 3 4
rfovcnvf1od
⊢ ( 𝜑 → ( 𝐹 : 𝒫 ( 𝐴 × 𝐵 ) –1-1 -onto → ( 𝒫 𝐵 ↑m 𝐴 ) ∧ ◡ 𝐹 = ( 𝑓 ∈ ( 𝒫 𝐵 ↑m 𝐴 ) ↦ { 〈 𝑥 , 𝑦 〉 ∣ ( 𝑥 ∈ 𝐴 ∧ 𝑦 ∈ ( 𝑓 ‘ 𝑥 ) ) } ) ) )
6
5
simpld
⊢ ( 𝜑 → 𝐹 : 𝒫 ( 𝐴 × 𝐵 ) –1-1 -onto → ( 𝒫 𝐵 ↑m 𝐴 ) )