Nuprl Lemma : decide-decide
∀[x:Top + Top]. ∀[f1,f2,g,h:Top].
  (case case x of inl(z) => f1[z] | inr(z) => f2[z] of inl(z) => g[z] | inr(z) => h[z] ~ case x
   of inl(z) =>
   case f1[z] of inl(z) => g[z] | inr(z) => h[z]
   | inr(z) =>
   case f2[z] of inl(z) => g[z] | inr(z) => h[z])
Proof
Definitions occuring in Statement : 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
so_apply: x[s]
, 
decide: case b of inl(x) => s[x] | inr(y) => t[y]
, 
union: left + right
, 
sqequal: s ~ t
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
Lemmas referenced : 
top_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
unionElimination, 
thin, 
sqequalRule, 
sqequalAxiom, 
lemma_by_obid, 
hypothesis, 
sqequalHypSubstitution, 
isect_memberEquality, 
isectElimination, 
hypothesisEquality, 
because_Cache, 
unionEquality
Latex:
\mforall{}[x:Top  +  Top].  \mforall{}[f1,f2,g,h:Top].
    (case  case  x  of  inl(z)  =>  f1[z]  |  inr(z)  =>  f2[z]  of  inl(z)  =>  g[z]  |  inr(z)  =>  h[z]  \msim{}  case  x
      of  inl(z)  =>
      case  f1[z]  of  inl(z)  =>  g[z]  |  inr(z)  =>  h[z]
      |  inr(z)  =>
      case  f2[z]  of  inl(z)  =>  g[z]  |  inr(z)  =>  h[z])
Date html generated:
2016_05_15-PM-03_25_06
Last ObjectModification:
2015_12_27-PM-01_06_35
Theory : general
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