Nuprl Lemma : member-fset-constrained-image-iff
∀[T,A:Type]. ∀[eqt:EqDecider(T)]. ∀[eqa:EqDecider(A)]. ∀[f:T ⟶ A]. ∀[P:A ⟶ 𝔹]. ∀[s:fset(T)]. ∀[a:A].
  uiff(a ∈ f"(s) s.t. P;↓∃x:T. (x ∈ s ∧ (a = (f x) ∈ A) ∧ (↑(P a))))
Proof
Definitions occuring in Statement : 
fset-constrained-image: f"(s) s.t. P, 
fset-member: a ∈ s, 
fset: fset(T), 
deq: EqDecider(T), 
assert: ↑b, 
bool: 𝔹, 
uiff: uiff(P;Q), 
uall: ∀[x:A]. B[x], 
exists: ∃x:A. B[x], 
squash: ↓T, 
and: P ∧ Q, 
apply: f a, 
function: x:A ⟶ B[x], 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
fset-constrained-image: f"(s) s.t. P, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
member: t ∈ T, 
squash: ↓T, 
exists: ∃x:A. B[x], 
prop: ℙ, 
cand: A c∧ B, 
uall: ∀[x:A]. B[x], 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
or: P ∨ Q, 
sq_type: SQType(T), 
guard: {T}, 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
top: Top, 
not: ¬A, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
fset-member_wf, 
equal_wf, 
assert_wf, 
squash_wf, 
exists_wf, 
ifthenelse_wf, 
fset_wf, 
fset-singleton_wf, 
empty-fset_wf, 
bool_wf, 
eqtt_to_assert, 
member-fset-singleton, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
mem_empty_lemma, 
assert_elim, 
and_wf, 
not_assert_elim, 
btrue_neq_bfalse, 
iff_weakening_uiff, 
f-union_wf, 
member-f-union, 
fset-member_witness, 
uiff_wf, 
fset-constrained-image_wf, 
deq_wf, 
bool_cases, 
assert_functionality_wrt_uiff, 
assert_of_bnot
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
cut, 
independent_pairFormation, 
isect_memberFormation, 
introduction, 
sqequalHypSubstitution, 
imageElimination, 
productElimination, 
thin, 
dependent_pairFormation, 
hypothesisEquality, 
productEquality, 
extract_by_obid, 
isectElimination, 
cumulativity, 
hypothesis, 
applyEquality, 
functionExtensionality, 
sqequalRule, 
imageMemberEquality, 
baseClosed, 
lambdaEquality, 
lambdaFormation, 
unionElimination, 
equalityElimination, 
because_Cache, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
promote_hyp, 
dependent_functionElimination, 
instantiate, 
independent_functionElimination, 
voidElimination, 
isect_memberEquality, 
voidEquality, 
dependent_set_memberEquality, 
applyLambdaEquality, 
setElimination, 
rename, 
addLevel, 
functionEquality, 
universeEquality, 
independent_pairEquality
Latex:
\mforall{}[T,A:Type].  \mforall{}[eqt:EqDecider(T)].  \mforall{}[eqa:EqDecider(A)].  \mforall{}[f:T  {}\mrightarrow{}  A].  \mforall{}[P:A  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[s:fset(T)].
\mforall{}[a:A].
    uiff(a  \mmember{}  f"(s)  s.t.  P;\mdownarrow{}\mexists{}x:T.  (x  \mmember{}  s  \mwedge{}  (a  =  (f  x))  \mwedge{}  (\muparrow{}(P  a))))
Date html generated:
2017_04_17-AM-09_21_15
Last ObjectModification:
2017_02_27-PM-05_24_13
Theory : finite!sets
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