Nuprl Lemma : is-list-if-has-value-decomp
∀t:ListLike
  ((t)↓
  ⇒ (((↑isaxiom(t)) ∧ (t = Ax ∈ Unit)) ∨ ((↑ispair(t)) ∧ (∃a:Top. ∃b:ListLike. (t = <a, b> ∈ (Top × ListLike))))))
Proof
Definitions occuring in Statement : 
is-list-if-has-value: ListLike, 
has-value: (a)↓, 
assert: ↑b, 
bfalse: ff, 
btrue: tt, 
top: Top, 
ispair: if z is a pair then a otherwise b, 
isaxiom: if z = Ax then a otherwise b, 
all: ∀x:A. B[x], 
exists: ∃x:A. B[x], 
implies: P ⇒ Q, 
or: P ∨ Q, 
and: P ∧ Q, 
unit: Unit, 
pair: <a, b>, 
product: x:A × B[x], 
equal: s = t ∈ T, 
axiom: Ax
Definitions unfolded in proof : 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
member: t ∈ T, 
uall: ∀[x:A]. B[x], 
prop: ℙ, 
b-union: A ⋃ B, 
tunion: ⋃x:A.B[x], 
bool: 𝔹, 
unit: Unit, 
ifthenelse: if b then t else f fi , 
pi2: snd(t), 
or: P ∨ Q, 
assert: ↑b, 
btrue: tt, 
and: P ∧ Q, 
true: True, 
exists: ∃x:A. B[x], 
bfalse: ff, 
false: False, 
subtype_rel: A ⊆r B, 
so_apply: x[s], 
so_lambda: λ2x.t[x], 
uimplies: b supposing a, 
ext-eq: A ≡ B
Lemmas referenced : 
is-list-if-has-value-hv-prp, 
is-list-if-has-value_wf, 
istype-assert, 
istype-top, 
istype-void, 
product-value-type, 
equal-value-type, 
bunion-value-type, 
top_wf, 
unit_wf2, 
b-union_wf, 
termination, 
is-list-if-has-value-ext, 
bfalse_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
lambdaFormation_alt, 
universeIsType, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
inhabitedIsType, 
imageElimination, 
productElimination, 
unionElimination, 
equalityElimination, 
sqequalRule, 
inlEquality_alt, 
closedConclusion, 
independent_pairEquality, 
axiomEquality, 
natural_numberEquality, 
productIsType, 
equalityIsType2, 
because_Cache, 
baseClosed, 
inrEquality_alt, 
dependent_pairEquality_alt, 
equalityIsType1, 
voidElimination, 
equalityTransitivity, 
equalitySymmetry, 
dependent_functionElimination, 
independent_functionElimination, 
applyEquality, 
lambdaEquality_alt, 
intEquality, 
independent_isectElimination, 
productEquality
Latex:
\mforall{}t:ListLike
    ((t)\mdownarrow{}  {}\mRightarrow{}  (((\muparrow{}isaxiom(t))  \mwedge{}  (t  =  Ax))  \mvee{}  ((\muparrow{}ispair(t))  \mwedge{}  (\mexists{}a:Top.  \mexists{}b:ListLike.  (t  =  <a,  b>)))))
Date html generated:
2019_10_16-AM-11_38_04
Last ObjectModification:
2018_10_31-PM-02_27_33
Theory : eval!all
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