Nuprl Lemma : istype-inr-sqeq-inl
∀[a,b:Top].  istype(inr b  ~ inl a)
Proof
Definitions occuring in Statement : 
istype: istype(T)
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
inr: inr x 
, 
inl: inl x
, 
sqequal: s ~ t
Definitions unfolded in proof : 
false: False
, 
not: ¬A
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
squash: ↓T
, 
prop: ℙ
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
rev_implies: P 
⇐ Q
, 
true: True
, 
subtype_rel: A ⊆r B
Lemmas referenced : 
member_wf, 
squash_wf, 
true_wf, 
istype-universe, 
not-inl-sqeq-inr, 
istype-sqequal, 
equal_wf, 
subtype_rel_self, 
istype-top
Rules used in proof : 
voidElimination, 
independent_functionElimination, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
Error :universeIsType, 
pointwiseFunctionality, 
sqequalExtensionalEquality, 
cut, 
applyEquality, 
thin, 
instantiate, 
Error :lambdaEquality_alt, 
sqequalHypSubstitution, 
imageElimination, 
introduction, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
universeEquality, 
independent_pairFormation, 
Error :lambdaFormation_alt, 
because_Cache, 
sqequalRule, 
baseApply, 
closedConclusion, 
baseClosed, 
imageMemberEquality, 
natural_numberEquality, 
Error :inhabitedIsType
Latex:
\mforall{}[a,b:Top].    istype(inr  b    \msim{}  inl  a)
Date html generated:
2019_06_20-PM-01_04_24
Last ObjectModification:
2019_06_20-PM-01_01_40
Theory : union
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