Nuprl Lemma : length-append
∀[as,bs:Top].  (||as @ bs|| ~ ||as|| + ||bs||)
Proof
Definitions occuring in Statement : 
length: ||as||
, 
append: as @ bs
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
add: n + m
, 
sqequal: s ~ t
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
append: as @ bs
, 
length: ||as||
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
uimplies: b supposing a
, 
strict1: strict1(F)
, 
and: P ∧ Q
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
list_ind: list_ind, 
has-value: (a)↓
, 
prop: ℙ
, 
or: P ∨ Q
, 
squash: ↓T
, 
guard: {T}
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
top: Top
Lemmas referenced : 
length-wf-has-value, 
zero-add-base, 
add-commutes, 
add-associates, 
top_wf, 
sqle_wf_base, 
length_of_cons_lemma, 
int-value-type, 
value-type-has-value, 
is-exception_wf, 
base_wf, 
has-value_wf_base, 
sqequal-list_ind
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
thin, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
baseClosed, 
independent_isectElimination, 
independent_pairFormation, 
lambdaFormation, 
callbyvalueCallbyvalue, 
hypothesis, 
callbyvalueReduce, 
baseApply, 
closedConclusion, 
hypothesisEquality, 
callbyvalueExceptionCases, 
inlFormation, 
imageMemberEquality, 
imageElimination, 
exceptionSqequal, 
inrFormation, 
callbyvalueAdd, 
productElimination, 
because_Cache, 
equalityTransitivity, 
equalitySymmetry, 
addExceptionCases, 
intEquality, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
sqequalAxiom, 
natural_numberEquality, 
divergentSqle, 
sqleRule, 
sqleReflexivity
Latex:
\mforall{}[as,bs:Top].    (||as  @  bs||  \msim{}  ||as||  +  ||bs||)
Date html generated:
2016_05_14-AM-06_35_06
Last ObjectModification:
2016_01_14-PM-08_23_09
Theory : list_0
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