Nuprl Lemma : setmem-set-add
∀a,b,x:coSet{i:l}.  ((x ∈ a + b) 
⇐⇒ (x ∈ a) ∨ (x ∈ b))
Proof
Definitions occuring in Statement : 
set-add: a + b
, 
setmem: (x ∈ s)
, 
coSet: coSet{i:l}
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
Definitions unfolded in proof : 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
subtype_rel: A ⊆r B
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
set-add: a + b
, 
mk-coset: mk-coset(T;f)
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
exists: ∃x:A. B[x]
, 
prop: ℙ
, 
rev_implies: P 
⇐ Q
, 
or: P ∨ Q
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
guard: {T}
Lemmas referenced : 
subtype_coSet, 
coSet_subtype, 
setmem-mk-coset, 
setmem_wf, 
set-add_wf, 
mk-coset_wf, 
or_wf, 
coSet_wf, 
seteq_wf, 
exists_wf, 
equal_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation, 
hypothesis_subsumption, 
cut, 
introduction, 
extract_by_obid, 
hypothesis, 
hypothesisEquality, 
applyEquality, 
sqequalHypSubstitution, 
sqequalRule, 
productElimination, 
thin, 
independent_pairFormation, 
isectElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
because_Cache, 
unionElimination, 
inlFormation, 
dependent_pairFormation, 
lambdaEquality, 
inrFormation, 
inlEquality, 
equalityTransitivity, 
equalitySymmetry, 
unionEquality, 
dependent_functionElimination, 
independent_functionElimination, 
inrEquality
Latex:
\mforall{}a,b,x:coSet\{i:l\}.    ((x  \mmember{}  a  +  b)  \mLeftarrow{}{}\mRightarrow{}  (x  \mmember{}  a)  \mvee{}  (x  \mmember{}  b))
Date html generated:
2019_10_31-AM-06_33_24
Last ObjectModification:
2018_08_21-PM-02_01_22
Theory : constructive!set!theory
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