Nuprl Lemma : has-value-extensionality
∀[a,b:Base].  (a)↓ = (b)↓ ∈ ℙ supposing (a)↓ 
⇐⇒ (b)↓
Proof
Definitions occuring in Statement : 
has-value: (a)↓
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
prop: ℙ
, 
iff: P 
⇐⇒ Q
, 
base: Base
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
has-value: (a)↓
, 
prop: ℙ
, 
implies: P 
⇒ Q
, 
rev_implies: P 
⇐ Q
, 
squash: ↓T
Lemmas referenced : 
has-value_wf_base, 
istype-base
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
sqequalHypSubstitution, 
productElimination, 
thin, 
sqleExtensionalEquality, 
independent_pairFormation, 
Error :lambdaFormation_alt, 
independent_functionElimination, 
hypothesis, 
Error :universeIsType, 
extract_by_obid, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
imageMemberEquality, 
baseClosed, 
Error :productIsType, 
Error :functionIsType, 
because_Cache, 
Error :isect_memberEquality_alt, 
axiomEquality, 
Error :isectIsTypeImplies, 
Error :inhabitedIsType
Latex:
\mforall{}[a,b:Base].    (a)\mdownarrow{}  =  (b)\mdownarrow{}  supposing  (a)\mdownarrow{}  \mLeftarrow{}{}\mRightarrow{}  (b)\mdownarrow{}
Date html generated:
2019_06_20-AM-11_20_34
Last ObjectModification:
2018_10_16-PM-01_47_32
Theory : call!by!value_1
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