Nuprl Lemma : decide-simple-int_eq
∀[a,b,c,d:Top].  (case if a=b  then inl ⋅  else (inr ⋅ ) of inl() => c | inr() => d ~ if a=b  then c  else d)
Proof
Definitions occuring in Statement : 
it: ⋅
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
int_eq: if a=b  then c  else d
, 
decide: case b of inl(x) => s[x] | inr(y) => t[y]
, 
inr: inr x 
, 
inl: inl x
, 
sqequal: s ~ t
Definitions unfolded in proof : 
top: Top
, 
it: ⋅
, 
uall: ∀[x:A]. B[x]
, 
so_lambda: so_lambda(x,y,z,w.t[x; y; z; w])
, 
member: t ∈ T
, 
so_apply: x[s1;s2;s3;s4]
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
uimplies: b supposing a
, 
strict4: strict4(F)
, 
and: P ∧ Q
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
has-value: (a)↓
, 
prop: ℙ
, 
guard: {T}
, 
or: P ∨ Q
, 
squash: ↓T
Lemmas referenced : 
lifting-strict-int_eq, 
top_wf, 
equal_wf, 
has-value_wf_base, 
base_wf, 
is-exception_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
baseClosed, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
independent_isectElimination, 
independent_pairFormation, 
lambdaFormation, 
callbyvalueDecide, 
hypothesis, 
hypothesisEquality, 
equalityTransitivity, 
equalitySymmetry, 
unionEquality, 
unionElimination, 
sqleReflexivity, 
dependent_functionElimination, 
independent_functionElimination, 
baseApply, 
closedConclusion, 
decideExceptionCases, 
inrFormation, 
because_Cache, 
imageMemberEquality, 
imageElimination, 
exceptionSqequal, 
inlFormation, 
isect_memberFormation, 
sqequalAxiom, 
isectEquality
Latex:
\mforall{}[a,b,c,d:Top].
    (case  if  a=b    then  inl  \mcdot{}    else  (inr  \mcdot{}  )  of  inl()  =>  c  |  inr()  =>  d  \msim{}  if  a=b    then  c    else  d)
Date html generated:
2017_10_01-AM-08_39_30
Last ObjectModification:
2017_07_26-PM-04_27_33
Theory : untyped!computation
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