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Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Peter Mazsa
Preparatory theorems
idinxpssinxp
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 , 6-Mar-2019)
Ref
Expression
Assertion
idinxpssinxp
⊢ I ∩ A × B ⊆ R ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x = y → x R y
Proof
Step
Hyp
Ref
Expression
1
inxpss2
⊢ I ∩ A × B ⊆ R ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x I y → x R y
2
ideqg
⊢ y ∈ V → x I y ↔ x = y
3
2
elv
⊢ x I y ↔ x = y
4
3
imbi1i
⊢ x I y → x R y ↔ x = y → x R y
5
4
2ralbii
⊢ ∀ x ∈ A ∀ y ∈ B x I y → x R y ↔ ∀ x ∈ A ∀ y ∈ B x = y → x R y
6
1 5
bitri
⊢ I ∩ A × B ⊆ R ∩ A × B ↔ ∀ x ∈ A ∀ y ∈ B x = y → x R y