Nuprl Lemma : setmem-mkset
∀T:Type. ∀f:T ⟶ Set{i:l}. ∀x:Set{i:l}.  ((x ∈ {f[t] | t ∈ T}) ⇐⇒ ∃t:T. seteq(x;f[t]))
Proof
Definitions occuring in Statement : 
setmem: (x ∈ s), 
seteq: seteq(s1;s2), 
mkset: {f[t] | t ∈ T}, 
Set: Set{i:l}, 
so_apply: x[s], 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
iff: P ⇐⇒ Q, 
function: x:A ⟶ B[x], 
universe: Type
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
mkset: {f[t] | t ∈ T}, 
set-item: set-item(s;x), 
set-dom: set-dom(s), 
pi1: fst(t), 
pi2: snd(t), 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
implies: P ⇒ Q, 
member: t ∈ T, 
prop: ℙ, 
uall: ∀[x:A]. B[x], 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
rev_implies: P ⇐ Q, 
exists: ∃x:A. B[x]
Lemmas referenced : 
exists_wf, 
seteq_wf, 
setmem-iff, 
mkset_wf, 
setmem_wf, 
iff_wf, 
set-dom_wf, 
set-item_wf, 
Set_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
cut, 
sqequalRule, 
independent_pairFormation, 
hypothesis, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
lambdaEquality, 
applyEquality, 
because_Cache, 
addLevel, 
productElimination, 
impliesFunctionality, 
dependent_functionElimination, 
independent_functionElimination, 
functionEquality, 
cumulativity, 
universeEquality
Latex:
\mforall{}T:Type.  \mforall{}f:T  {}\mrightarrow{}  Set\{i:l\}.  \mforall{}x:Set\{i:l\}.    ((x  \mmember{}  \{f[t]  |  t  \mmember{}  T\})  \mLeftarrow{}{}\mRightarrow{}  \mexists{}t:T.  seteq(x;f[t]))
 Date html generated: 
2018_05_22-PM-09_49_32
 Last ObjectModification: 
2018_05_16-PM-01_31_29
Theory : constructive!set!theory
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