Nuprl Lemma : decide_wf

∀[T1,T2,T3:Type]. ∀[x:T1 + T2]. ∀[l:T1 ⟶ T3]. ∀[r:T2 ⟶ T3].  (case x of inl(a) => l[a] | inr(b) => r[b] ∈ T3)


Proof




Definitions occuring in Statement :  uall: ∀[x:A]. B[x],  so_apply: x[s],  member: t ∈ T,  function: x:A ⟶ B[x],  decide: case b of inl(x) => s[x] | inr(y) => t[y],  union: left + right,  universe: Type
Definitions unfolded in proof :  uall: ∀[x:A]. B[x],  member: t ∈ T,  all: ∀x:A. B[x],  implies: P ⇒ Q,  so_apply: x[s],  prop: ℙ
Lemmas referenced :  equal_wf
Rules used in proof :  sqequalSubstitution,  sqequalTransitivity,  computationStep,  sqequalReflexivity,  isect_memberFormation,  introduction,  cut,  hypothesisEquality,  equalityTransitivity,  hypothesis,  equalitySymmetry,  thin,  unionEquality,  lambdaFormation,  unionElimination,  sqequalRule,  applyEquality,  extract_by_obid,  sqequalHypSubstitution,  isectElimination,  dependent_functionElimination,  independent_functionElimination,  axiomEquality,  functionEquality,  isect_memberEquality,  because_Cache,  universeEquality

Latex:
\mforall{}[T1,T2,T3:Type].  \mforall{}[x:T1  +  T2].  \mforall{}[l:T1  {}\mrightarrow{}  T3].  \mforall{}[r:T2  {}\mrightarrow{}  T3].
    (case  x  of  inl(a)  =>  l[a]  |  inr(b)  =>  r[b]  \mmember{}  T3)



Date html generated: 2019_10_15-AM-11_06_47
Last ObjectModification: 2018_08_21-PM-01_58_34

Theory : general


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