Nuprl Lemma : pcw-path-coPath_wf
∀[A:𝕌']. ∀[B:A ⟶ Type]. ∀[w:coW(A;a.B[a])]. ∀[p:Path].
  ∀[n:ℕ]
    ((pcw-path-coPath(n;p) ∈ copath(a.B[a];w))
    ∧ ((copath-length(pcw-path-coPath(n;p)) = n ∈ ℤ)
      ⇒ (copath-at(w;pcw-path-coPath(n;p)) = (fst(snd((p n)))) ∈ coW(A;a.B[a])))) 
  supposing StepAgree(p 0;⋅;w)
Proof
Definitions occuring in Statement : 
pcw-path-coPath: pcw-path-coPath(n;p), 
copath-length: copath-length(p), 
copath-at: copath-at(w;p), 
copath: copath(a.B[a];w), 
coW: coW(A;a.B[a]), 
pcw-path: Path, 
pcw-step-agree: StepAgree(s;p1;w), 
nat: ℕ, 
it: ⋅, 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x], 
so_apply: x[s], 
pi1: fst(t), 
pi2: snd(t), 
implies: P ⇒ Q, 
and: P ∧ Q, 
unit: Unit, 
member: t ∈ T, 
apply: f a, 
function: x:A ⟶ B[x], 
natural_number: $n, 
int: ℤ, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
coW-item: coW-item(w;b), 
ext-eq: A ≡ B, 
squash: ↓T, 
coW-dom: coW-dom(a.B[a];w), 
pcw-steprel: StepRel(s1;s2), 
bfalse: ff, 
it: ⋅, 
unit: Unit, 
bool: 𝔹, 
cand: A c∧ B, 
let: let, 
coPath-at: coPath-at(n;w;p), 
pi1: fst(t), 
pi2: snd(t), 
copath-nil: (), 
spreadn: spread3, 
pcw-step-agree: StepAgree(s;p1;w), 
copath-at: copath-at(w;p), 
pcw-step: pcw-step(P;p.A[p];p,a.B[p; a];p,a,b.C[p; a; b]), 
btrue: tt, 
ifthenelse: if b then t else f fi , 
eq_int: (i =z j), 
pcw-path-coPath: pcw-path-coPath(n;p), 
coW: coW(A;a.B[a]), 
pcw-path: Path, 
so_apply: x[s1;s2;s3], 
so_lambda: so_lambda(x,y,z.t[x; y; z]), 
so_apply: x[s1;s2], 
so_lambda: λ2x y.t[x; y], 
so_lambda: λ2x.t[x], 
true: True, 
less_than': less_than'(a;b), 
le: A ≤ B, 
top: Top, 
subtype_rel: A ⊆r B, 
subtract: n - m, 
uiff: uiff(P;Q), 
rev_implies: P ⇐ Q, 
not: ¬A, 
iff: P ⇐⇒ Q, 
or: P ∨ Q, 
decidable: Dec(P), 
all: ∀x:A. B[x], 
and: P ∧ Q, 
so_apply: x[s], 
prop: ℙ, 
guard: {T}, 
ge: i ≥ j , 
false: False, 
implies: P ⇒ Q, 
nat: ℕ, 
member: t ∈ T, 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x]
Lemmas referenced : 
coW-item_wf, 
copath-at-extend, 
iff_weakening_equal, 
subtype_rel_self, 
true_wf, 
squash_wf, 
coW-dom_wf, 
pi1_wf, 
subtype_rel_weakening, 
coW-ext, 
copath-extend_wf, 
assert_of_bnot, 
eqff_to_assert, 
iff_weakening_uiff, 
iff_transitivity, 
assert_of_eq_int, 
eqtt_to_assert, 
uiff_transitivity, 
le_weakening2, 
pcw-steprel_wf, 
not_wf, 
bnot_wf, 
le_weakening, 
assert_wf, 
bool_wf, 
eq_int_wf, 
int_subtype_base, 
copath-length_wf, 
subtract-add-cancel, 
not-le-2, 
equal-wf-base, 
and_wf, 
top_wf, 
param-co-W_wf, 
subtype_rel-equal, 
equal_wf, 
equal-wf-T-base, 
pcw-step_wf, 
copath-nil_wf, 
copath_length_nil_lemma, 
coW_wf, 
pcw-path_wf, 
le_wf, 
it_wf, 
unit_wf2, 
pcw-step-agree_wf, 
nat_wf, 
le-add-cancel, 
add-zero, 
add_functionality_wrt_le, 
add-commutes, 
add-swap, 
add-associates, 
minus-minus, 
minus-add, 
minus-one-mul-top, 
zero-add, 
minus-one-mul, 
condition-implies-le, 
less-iff-le, 
not-ge-2, 
false_wf, 
subtract_wf, 
decidable__le, 
less_than_wf, 
ge_wf, 
less_than_irreflexivity, 
less_than_transitivity1, 
nat_properties
Rules used in proof : 
imageMemberEquality, 
imageElimination, 
hypothesis_subsumption, 
hyp_replacement, 
impliesFunctionality, 
equalityElimination, 
closedConclusion, 
baseApply, 
applyLambdaEquality, 
baseClosed, 
productEquality, 
functionExtensionality, 
independent_pairEquality, 
universeEquality, 
functionEquality, 
dependent_set_memberEquality, 
cumulativity, 
instantiate, 
equalitySymmetry, 
equalityTransitivity, 
because_Cache, 
minusEquality, 
intEquality, 
voidEquality, 
isect_memberEquality, 
applyEquality, 
addEquality, 
productElimination, 
independent_pairFormation, 
unionElimination, 
axiomEquality, 
dependent_functionElimination, 
lambdaEquality, 
sqequalRule, 
voidElimination, 
independent_functionElimination, 
independent_isectElimination, 
natural_numberEquality, 
lambdaFormation, 
intWeakElimination, 
rename, 
setElimination, 
hypothesis, 
hypothesisEquality, 
thin, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
cut, 
introduction, 
isect_memberFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}[A:\mBbbU{}'].  \mforall{}[B:A  {}\mrightarrow{}  Type].  \mforall{}[w:coW(A;a.B[a])].  \mforall{}[p:Path].
    \mforall{}[n:\mBbbN{}]
        ((pcw-path-coPath(n;p)  \mmember{}  copath(a.B[a];w))
        \mwedge{}  ((copath-length(pcw-path-coPath(n;p))  =  n)
            {}\mRightarrow{}  (copath-at(w;pcw-path-coPath(n;p))  =  (fst(snd((p  n))))))) 
    supposing  StepAgree(p  0;\mcdot{};w)
Date html generated:
2018_07_25-PM-01_41_40
Last ObjectModification:
2018_07_23-AM-11_52_52
Theory : co-recursion
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