Nuprl Lemma : copath-eta2
∀[A:𝕌']. ∀[B:A ⟶ Type]. ∀[w:coW(A;a.B[a])]. ∀[p:copath(a.B[a];w)]. ∀[q:coW-dom(a.B[a];w)].
  (0 < copath-length(p)
  
⇒ (q = copath-hd(p) ∈ coW-dom(a.B[a];w))
  
⇒ (copath-cons(q;copath-tl(p)) = p ∈ copath(a.B[a];w)))
Proof
Definitions occuring in Statement : 
copath-cons: copath-cons(b;x)
, 
copath-tl: copath-tl(x)
, 
copath-hd: copath-hd(p)
, 
copath-length: copath-length(p)
, 
copath: copath(a.B[a];w)
, 
coW-dom: coW-dom(a.B[a];w)
, 
coW: coW(A;a.B[a])
, 
less_than: a < b
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
implies: P 
⇒ Q
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
implies: P 
⇒ Q
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
uimplies: b supposing a
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
nat: ℕ
, 
squash: ↓T
, 
true: True
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
copath-eta, 
equal_wf, 
coW-dom_wf, 
copath-hd_wf, 
less_than_wf, 
copath-length_wf, 
nat_wf, 
copath_wf, 
coW_wf, 
copath-tl_wf, 
subtype_rel-equal, 
coW-item_wf, 
subtype_rel_self, 
iff_weakening_equal, 
squash_wf, 
true_wf, 
copath-cons_wf
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
hypothesis, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
lambdaFormation, 
sqequalRule, 
lambdaEquality, 
applyEquality, 
independent_isectElimination, 
natural_numberEquality, 
setElimination, 
rename, 
instantiate, 
cumulativity, 
functionEquality, 
universeEquality, 
functionExtensionality, 
independent_functionElimination, 
imageElimination, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
imageMemberEquality, 
baseClosed, 
productElimination
Latex:
\mforall{}[A:\mBbbU{}'].  \mforall{}[B:A  {}\mrightarrow{}  Type].  \mforall{}[w:coW(A;a.B[a])].  \mforall{}[p:copath(a.B[a];w)].  \mforall{}[q:coW-dom(a.B[a];w)].
    (0  <  copath-length(p)  {}\mRightarrow{}  (q  =  copath-hd(p))  {}\mRightarrow{}  (copath-cons(q;copath-tl(p))  =  p))
Date html generated:
2018_07_25-PM-01_40_20
Last ObjectModification:
2018_06_14-AM-10_58_10
Theory : co-recursion
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