Database
CLASSICAL FIRST-ORDER LOGIC WITH EQUALITY
Uniqueness and unique existence
Unique existence: the unique existential quantifier
eupicka
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eupickb
Metamath Proof Explorer
Ascii
Unicode
Theorem
eupicka
Description:
Version of
eupick
with closed formulas.
(Contributed by
NM
, 6-Sep-2008)
Ref
Expression
Assertion
eupicka
⊢
∃!
x
φ
∧
∃
x
φ
∧
ψ
→
∀
x
φ
→
ψ
Proof
Step
Hyp
Ref
Expression
1
nfeu1
⊢
Ⅎ
x
∃!
x
φ
2
nfe1
⊢
Ⅎ
x
∃
x
φ
∧
ψ
3
1
2
nfan
⊢
Ⅎ
x
∃!
x
φ
∧
∃
x
φ
∧
ψ
4
eupick
⊢
∃!
x
φ
∧
∃
x
φ
∧
ψ
→
φ
→
ψ
5
3
4
alrimi
⊢
∃!
x
φ
∧
∃
x
φ
∧
ψ
→
∀
x
φ
→
ψ