Nuprl Lemma : copath-eta
∀[A:𝕌']. ∀[B:A ⟶ Type]. ∀[w:coW(A;a.B[a])]. ∀[p:copath(a.B[a];w)].
  (0 < copath-length(p) ⇒ (copath-cons(copath-hd(p);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: 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, 
prop: ℙ, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
subtype_rel: A ⊆r B, 
nat: ℕ, 
copath: copath(a.B[a];w), 
coPath: coPath(a.B[a];w;n), 
copath-length: copath-length(p), 
pi1: fst(t), 
false: False, 
guard: {T}, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
top: Top, 
or: P ∨ Q, 
sq_type: SQType(T), 
uiff: uiff(P;Q), 
and: P ∧ Q, 
ifthenelse: if b then t else f fi , 
btrue: tt, 
iff: P ⇐⇒ Q, 
not: ¬A, 
rev_implies: P ⇐ Q, 
bfalse: ff
Lemmas referenced : 
less_than_wf, 
copath-length_wf, 
nat_wf, 
copath_wf, 
coW_wf, 
copath-cons-hd-tl, 
eq_int_wf, 
less_than_transitivity1, 
le_weakening, 
less_than_irreflexivity, 
assert_wf, 
bnot_wf, 
not_wf, 
equal-wf-T-base, 
bool_cases, 
subtype_base_sq, 
bool_wf, 
bool_subtype_base, 
eqtt_to_assert, 
assert_of_eq_int, 
eqff_to_assert, 
iff_transitivity, 
iff_weakening_uiff, 
assert_of_bnot
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
lambdaFormation, 
hypothesis, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
natural_numberEquality, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
applyEquality, 
setElimination, 
rename, 
dependent_functionElimination, 
axiomEquality, 
because_Cache, 
isect_memberEquality, 
instantiate, 
cumulativity, 
functionEquality, 
universeEquality, 
productElimination, 
independent_pairEquality, 
equalityTransitivity, 
equalitySymmetry, 
independent_isectElimination, 
independent_functionElimination, 
voidElimination, 
intEquality, 
baseClosed, 
voidEquality, 
unionElimination, 
independent_pairFormation, 
impliesFunctionality
Latex:
\mforall{}[A:\mBbbU{}'].  \mforall{}[B:A  {}\mrightarrow{}  Type].  \mforall{}[w:coW(A;a.B[a])].  \mforall{}[p:copath(a.B[a];w)].
    (0  <  copath-length(p)  {}\mRightarrow{}  (copath-cons(copath-hd(p);copath-tl(p))  =  p))
Date html generated:
2018_07_25-PM-01_40_16
Last ObjectModification:
2018_06_14-AM-10_48_50
Theory : co-recursion
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