Step
*
of Lemma
fset-some-iff
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[P:T ⟶ 𝔹]. ∀[s:fset(T)]. uiff(fset-some(s;x.P[x]);¬¬(∃x:T. (x ∈ s ∧ (↑P[x]))))
BY
{ ((Unfold `fset-some` 0 THEN Auto) THEN ParallelLast THEN All(\h. (RWO "assert-fset-null" h THEN Auto)⋅ )⋅) }
1
1. T : Type
2. eq : EqDecider(T)
3. P : T ⟶ 𝔹
4. s : fset(T)
5. ¬(∃x:T. (x ∈ s ∧ (↑P[x])))
⊢ {x ∈ s | P[x]} = {} ∈ fset(T)
2
1. T : Type
2. eq : EqDecider(T)
3. P : T ⟶ 𝔹
4. s : fset(T)
5. {x ∈ s | P[x]} = {} ∈ fset(T)
⊢ ¬(∃x:T. (x ∈ s ∧ (↑P[x])))
Latex:
Latex:
\mforall{}[T:Type]. \mforall{}[eq:EqDecider(T)]. \mforall{}[P:T {}\mrightarrow{} \mBbbB{}]. \mforall{}[s:fset(T)].
uiff(fset-some(s;x.P[x]);\mneg{}\mneg{}(\mexists{}x:T. (x \mmember{} s \mwedge{} (\muparrow{}P[x]))))
By
Latex:
((Unfold `fset-some` 0 THEN Auto)
THEN ParallelLast
THEN All(\mbackslash{}h. (RWO "assert-fset-null" h THEN Auto)\mcdot{} )\mcdot{})
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