Nuprl Lemma : length_append
∀[as,bs:Top List].  (||as @ bs|| = (||as|| + ||bs||) ∈ ℤ)
Proof
Definitions occuring in Statement : 
length: ||as||
, 
append: as @ bs
, 
list: T List
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
add: n + m
, 
int: ℤ
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
top: Top
Lemmas referenced : 
length-append, 
length_wf, 
top_wf, 
list_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
cut, 
lemma_by_obid, 
sqequalHypSubstitution, 
sqequalTransitivity, 
computationStep, 
isectElimination, 
thin, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
hypothesis, 
isect_memberFormation, 
introduction, 
addEquality, 
hypothesisEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
because_Cache
Latex:
\mforall{}[as,bs:Top  List].    (||as  @  bs||  =  (||as||  +  ||bs||))
Date html generated:
2016_05_14-AM-06_35_15
Last ObjectModification:
2015_12_26-PM-00_34_57
Theory : list_0
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