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Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Peter Mazsa
Preparatory theorems
inxpssidinxp
Metamath Proof Explorer
Description: Two ways to say that intersections with Cartesian products are in a
subclass relation, special case of inxpss2 . (Contributed by Peter
Mazsa , 4-Jul-2019)
Ref
Expression
Assertion
inxpssidinxp
⊢ R ∩ A × B ⊆ I ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x R y → x = y
Proof
Step
Hyp
Ref
Expression
1
inxpss2
⊢ R ∩ A × B ⊆ I ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x R y → x I y
2
ideqg
⊢ y ∈ V → x I y ↔ x = y
3
2
elv
⊢ x I y ↔ x = y
4
3
imbi2i
⊢ x R y → x I y ↔ x R y → x = y
5
4
2ralbii
⊢ ∀ x ∈ A ∀ y ∈ B x R y → x I y ↔ ∀ x ∈ A ∀ y ∈ B x R y → x = y
6
1 5
bitri
⊢ R ∩ A × B ⊆ I ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x R y → x = y