Nuprl Lemma : decide2_wf
∀[T1,T2,T3,T4,T5:Type]. ∀[x:T1 + T2]. ∀[y:T3 + T4]. ∀[ll:T1 ⟶ T3 ⟶ T5]. ∀[lr:T1 ⟶ T4 ⟶ T5]. ∀[rl:T2 ⟶ T3 ⟶ T5].
∀[rr:T2 ⟶ T4 ⟶ T5].
  (case x,y
   of inl(a),inl(b) => ll[a;b]
    | inl(a),inr(b) => lr[a;b]
    | inr(a),inl(b) => rl[a;b]
    | inr(a),inr(b) => rr[a;b] ∈ T5)
Proof
Definitions occuring in Statement : 
decide2: decide2, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s1;s2]
, 
member: t ∈ T
, 
function: x:A ⟶ B[x]
, 
union: left + right
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
decide2: decide2, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
so_apply: x[s1;s2]
, 
prop: ℙ
Lemmas referenced : 
equal_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
hypothesisEquality, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
thin, 
because_Cache, 
lambdaFormation, 
unionElimination, 
applyEquality, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
dependent_functionElimination, 
independent_functionElimination, 
axiomEquality, 
functionEquality, 
isect_memberEquality, 
unionEquality, 
universeEquality
Latex:
\mforall{}[T1,T2,T3,T4,T5:Type].  \mforall{}[x:T1  +  T2].  \mforall{}[y:T3  +  T4].  \mforall{}[ll:T1  {}\mrightarrow{}  T3  {}\mrightarrow{}  T5].  \mforall{}[lr:T1  {}\mrightarrow{}  T4  {}\mrightarrow{}  T5].
\mforall{}[rl:T2  {}\mrightarrow{}  T3  {}\mrightarrow{}  T5].  \mforall{}[rr:T2  {}\mrightarrow{}  T4  {}\mrightarrow{}  T5].
    (case  x,y
      of  inl(a),inl(b)  =>  ll[a;b]
        |  inl(a),inr(b)  =>  lr[a;b]
        |  inr(a),inl(b)  =>  rl[a;b]
        |  inr(a),inr(b)  =>  rr[a;b]  \mmember{}  T5)
Date html generated:
2019_10_15-AM-11_14_45
Last ObjectModification:
2018_08_21-PM-01_59_31
Theory : general
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