Nuprl Lemma : member-f-union
∀[T,A:Type]. ∀[eqt:EqDecider(T)]. ∀[eqa:EqDecider(A)]. ∀[g:T ⟶ fset(A)]. ∀[s:fset(T)]. ∀[a:A].
  uiff(a ∈ f-union(eqt;eqa;s;x.g[x]);↓∃x:T. (x ∈ s ∧ a ∈ g[x]))
Proof
Definitions occuring in Statement : 
f-union: f-union(domeq;rngeq;s;x.g[x]), 
fset-member: a ∈ s, 
fset: fset(T), 
deq: EqDecider(T), 
uiff: uiff(P;Q), 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
exists: ∃x:A. B[x], 
squash: ↓T, 
and: P ∧ Q, 
function: x:A ⟶ B[x], 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
squash: ↓T, 
prop: ℙ, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
implies: P ⇒ Q, 
fset: fset(T), 
exists: ∃x:A. B[x], 
quotient: x,y:A//B[x; y], 
all: ∀x:A. B[x], 
iff: P ⇐⇒ Q, 
cand: A c∧ B, 
subtype_rel: A ⊆r B, 
guard: {T}, 
fset-member: a ∈ s, 
rev_implies: P ⇐ Q, 
decidable: Dec(P), 
or: P ∨ Q, 
sq_type: SQType(T), 
true: True, 
false: False, 
not: ¬A
Lemmas referenced : 
fset-member_wf, 
f-union_wf, 
fset-member_witness, 
squash_wf, 
exists_wf, 
fset_wf, 
deq_wf, 
equal-wf-base, 
list_wf, 
set-equal_wf, 
member-f-union-aux, 
l_exists_iff, 
l_member_wf, 
list_subtype_fset, 
assert-deq-member, 
decidable__fset-member, 
subtype_base_sq, 
int_subtype_base, 
set-equal-reflex, 
equal_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
independent_pairFormation, 
hypothesis, 
sqequalHypSubstitution, 
imageElimination, 
sqequalRule, 
imageMemberEquality, 
hypothesisEquality, 
thin, 
baseClosed, 
extract_by_obid, 
isectElimination, 
cumulativity, 
lambdaEquality, 
applyEquality, 
functionExtensionality, 
independent_functionElimination, 
productEquality, 
productElimination, 
independent_pairEquality, 
isect_memberEquality, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
functionEquality, 
universeEquality, 
pointwiseFunctionalityForEquality, 
pertypeElimination, 
dependent_functionElimination, 
setElimination, 
rename, 
setEquality, 
dependent_pairFormation, 
independent_isectElimination, 
unionElimination, 
instantiate, 
intEquality, 
natural_numberEquality, 
voidElimination, 
promote_hyp, 
lambdaFormation, 
pointwiseFunctionality
Latex:
\mforall{}[T,A:Type].  \mforall{}[eqt:EqDecider(T)].  \mforall{}[eqa:EqDecider(A)].  \mforall{}[g:T  {}\mrightarrow{}  fset(A)].  \mforall{}[s:fset(T)].  \mforall{}[a:A].
    uiff(a  \mmember{}  f-union(eqt;eqa;s;x.g[x]);\mdownarrow{}\mexists{}x:T.  (x  \mmember{}  s  \mwedge{}  a  \mmember{}  g[x]))
Date html generated:
2017_04_17-AM-09_19_10
Last ObjectModification:
2017_02_27-PM-05_22_45
Theory : finite!sets
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