Nuprl Lemma : length-is-colength
∀[t:Top]. (||t|| ~ colength(t))
Proof
Definitions occuring in Statement : 
length: ||as||
, 
colength: colength(L)
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
sqequal: s ~ t
Definitions unfolded in proof : 
colength: colength(L)
, 
length: ||as||
, 
list_ind: list_ind, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
, 
nat: ℕ
, 
implies: P 
⇒ Q
, 
false: False
, 
ge: i ≥ j 
, 
guard: {T}
, 
uimplies: b supposing a
, 
prop: ℙ
, 
fun_exp: f^n
, 
primrec: primrec(n;b;c)
, 
top: Top
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
not: ¬A
, 
rev_implies: P 
⇐ Q
, 
uiff: uiff(P;Q)
, 
subtract: n - m
, 
subtype_rel: A ⊆r B
, 
le: A ≤ B
, 
less_than': less_than'(a;b)
, 
true: True
, 
nat_plus: ℕ+
, 
has-value: (a)↓
Lemmas referenced : 
nat_properties, 
less_than_transitivity1, 
less_than_irreflexivity, 
ge_wf, 
less_than_wf, 
base_wf, 
strictness-apply, 
bottom-sqle, 
decidable__le, 
subtract_wf, 
false_wf, 
not-ge-2, 
less-iff-le, 
condition-implies-le, 
minus-one-mul, 
zero-add, 
minus-one-mul-top, 
minus-add, 
minus-minus, 
add-associates, 
add-swap, 
add-commutes, 
add_functionality_wrt_le, 
add-zero, 
le-add-cancel, 
fun_exp_unroll_1, 
istype-top, 
has-value-implies-dec-ispair-2, 
has-value_wf_base, 
is-exception_wf, 
bottom_diverge, 
exception-not-bottom, 
has-value-implies-dec-isaxiom-2, 
top_wf, 
equal_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
thin, 
sqequalSqle, 
lambdaFormation, 
fixpointLeast, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
hypothesis, 
setElimination, 
rename, 
intWeakElimination, 
natural_numberEquality, 
independent_isectElimination, 
independent_functionElimination, 
voidElimination, 
lambdaEquality, 
dependent_functionElimination, 
axiomSqleEquality, 
isect_memberEquality, 
voidEquality, 
unionElimination, 
independent_pairFormation, 
productElimination, 
addEquality, 
applyEquality, 
intEquality, 
minusEquality, 
because_Cache, 
dependent_set_memberEquality, 
axiomSqEquality, 
divergentSqle, 
callbyvalueCallbyvalue, 
callbyvalueReduce, 
sqleRule, 
baseApply, 
closedConclusion, 
baseClosed, 
sqleReflexivity, 
callbyvalueExceptionCases, 
exceptionSqequal, 
callbyvalueIsaxiom, 
callbyvalueSpread, 
equalityTransitivity, 
equalitySymmetry, 
productEquality, 
isaxiomExceptionCases, 
spreadExceptionCases
Latex:
\mforall{}[t:Top].  (||t||  \msim{}  colength(t))
Date html generated:
2019_06_20-PM-00_39_57
Last ObjectModification:
2018_09_26-PM-02_59_09
Theory : list_0
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