Nuprl Lemma : coPath-extend_wf
∀[A:𝕌']. ∀[B:A ⟶ Type]. ∀[n:ℕ]. ∀[w:coW(A;a.B[a])]. ∀[p:coPath(a.B[a];w;n)]. ∀[t:coW-dom(a.B[a];coPath-at(n;w;p))].
  (coPath-extend(n;p;t) ∈ coPath(a.B[a];w;n + 1))
Proof
Definitions occuring in Statement : 
coPath-extend: coPath-extend(n;p;t)
, 
coPath-at: coPath-at(n;w;p)
, 
coPath: coPath(a.B[a];w;n)
, 
coW-dom: coW-dom(a.B[a];w)
, 
coW: coW(A;a.B[a])
, 
nat: ℕ
, 
uall: ∀[x:A]. B[x]
, 
so_apply: x[s]
, 
member: t ∈ T
, 
function: x:A ⟶ B[x]
, 
add: n + m
, 
natural_number: $n
, 
universe: Type
Definitions unfolded in proof : 
nequal: a ≠ b ∈ T 
, 
assert: ↑b
, 
bnot: ¬bb
, 
sq_type: SQType(T)
, 
exists: ∃x:A. B[x]
, 
it: ⋅
, 
unit: Unit
, 
bool: 𝔹
, 
true: True
, 
top: Top
, 
uiff: uiff(P;Q)
, 
rev_implies: P 
⇐ Q
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
, 
decidable: Dec(P)
, 
not: ¬A
, 
less_than': less_than'(a;b)
, 
and: P ∧ Q
, 
le: A ≤ B
, 
subtype_rel: A ⊆r B
, 
all: ∀x:A. B[x]
, 
bfalse: ff
, 
btrue: tt
, 
ifthenelse: if b then t else f fi 
, 
subtract: n - m
, 
eq_int: (i =z j)
, 
coPath-at: coPath-at(n;w;p)
, 
coPath: coPath(a.B[a];w;n)
, 
coPath-extend: coPath-extend(n;p;t)
, 
so_apply: x[s]
, 
so_lambda: λ2x.t[x]
, 
prop: ℙ
, 
uimplies: b supposing a
, 
guard: {T}
, 
ge: i ≥ j 
, 
false: False
, 
implies: P 
⇒ Q
, 
nat: ℕ
, 
member: t ∈ T
, 
uall: ∀[x:A]. B[x]
Lemmas referenced : 
assert_of_bnot, 
iff_weakening_uiff, 
iff_transitivity, 
uiff_transitivity, 
zero-mul, 
add-mul-special, 
not-equal-2, 
not-le-2, 
coPath_subtype, 
neg_assert_of_eq_int, 
assert-bnot, 
bool_subtype_base, 
subtype_base_sq, 
bool_cases_sqequal, 
equal_wf, 
eqff_to_assert, 
assert_of_eq_int, 
eqtt_to_assert, 
not_wf, 
bnot_wf, 
le_weakening, 
assert_wf, 
int_subtype_base, 
equal-wf-base, 
bool_wf, 
eq_int_wf, 
nat_wf, 
le_weakening2, 
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, 
subtract_wf, 
decidable__le, 
le_wf, 
false_wf, 
top_wf, 
coW-item_wf, 
it_wf, 
coW_wf, 
coPath_wf, 
coPath-at_wf, 
coW-dom_wf, 
less_than_wf, 
ge_wf, 
less_than_irreflexivity, 
less_than_transitivity1, 
nat_properties
Rules used in proof : 
impliesFunctionality, 
productEquality, 
multiplyEquality, 
promote_hyp, 
dependent_pairFormation, 
equalityElimination, 
baseClosed, 
closedConclusion, 
baseApply, 
universeEquality, 
functionEquality, 
minusEquality, 
intEquality, 
voidEquality, 
addEquality, 
productElimination, 
unionElimination, 
independent_pairFormation, 
dependent_set_memberEquality, 
dependent_pairEquality, 
instantiate, 
because_Cache, 
functionExtensionality, 
applyEquality, 
cumulativity, 
equalitySymmetry, 
equalityTransitivity, 
axiomEquality, 
isect_memberEquality, 
dependent_functionElimination, 
lambdaEquality, 
voidElimination, 
independent_functionElimination, 
independent_isectElimination, 
natural_numberEquality, 
lambdaFormation, 
intWeakElimination, 
sqequalRule, 
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{}[n:\mBbbN{}].  \mforall{}[w:coW(A;a.B[a])].  \mforall{}[p:coPath(a.B[a];w;n)].
\mforall{}[t:coW-dom(a.B[a];coPath-at(n;w;p))].
    (coPath-extend(n;p;t)  \mmember{}  coPath(a.B[a];w;n  +  1))
Date html generated:
2018_07_25-PM-01_38_42
Last ObjectModification:
2018_07_18-PM-07_07_06
Theory : co-recursion
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