Nuprl Lemma : p-conditional-to-p-first
∀[A,B:Type]. ∀[f,g:A ⟶ (B + Top)].  ([f?g] = p-first([f; g]) ∈ (A ⟶ (B + Top)))
Proof
Definitions occuring in Statement : 
p-conditional: [f?g], 
p-first: p-first(L), 
cons: [a / b], 
nil: [], 
uall: ∀[x:A]. B[x], 
top: Top, 
function: x:A ⟶ B[x], 
union: left + right, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
p-first: p-first(L), 
p-conditional: [f?g], 
all: ∀x:A. B[x], 
top: Top, 
so_lambda: λ2x y.t[x; y], 
so_apply: x[s1;s2], 
can-apply: can-apply(f;x), 
implies: P ⇒ Q, 
isl: isl(x), 
ifthenelse: if b then t else f fi , 
btrue: tt, 
bfalse: ff, 
prop: ℙ
Lemmas referenced : 
top_wf, 
list_accum_cons_lemma, 
list_accum_nil_lemma, 
equal_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
functionExtensionality, 
hypothesisEquality, 
hypothesis, 
functionEquality, 
cumulativity, 
unionEquality, 
extract_by_obid, 
sqequalRule, 
sqequalHypSubstitution, 
isect_memberEquality, 
isectElimination, 
thin, 
axiomEquality, 
because_Cache, 
universeEquality, 
dependent_functionElimination, 
voidElimination, 
voidEquality, 
applyEquality, 
lambdaFormation, 
unionElimination, 
equalityTransitivity, 
equalitySymmetry, 
independent_functionElimination
Latex:
\mforall{}[A,B:Type].  \mforall{}[f,g:A  {}\mrightarrow{}  (B  +  Top)].    ([f?g]  =  p-first([f;  g]))
Date html generated:
2017_10_01-AM-09_14_10
Last ObjectModification:
2017_07_26-PM-04_49_21
Theory : general
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