Nuprl Lemma : length-mapfilter
∀[l,f,P:Top].  (||mapfilter(f;P;l)|| ~ ||filter(P;l)||)
Proof
Definitions occuring in Statement : 
mapfilter: mapfilter(f;P;L)
, 
length: ||as||
, 
filter: filter(P;l)
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
sqequal: s ~ t
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
mapfilter: mapfilter(f;P;L)
, 
top: Top
Lemmas referenced : 
map-length, 
top_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
hypothesis, 
sqequalAxiom, 
because_Cache
Latex:
\mforall{}[l,f,P:Top].    (||mapfilter(f;P;l)||  \msim{}  ||filter(P;l)||)
Date html generated:
2016_05_14-PM-01_29_36
Last ObjectModification:
2015_12_26-PM-05_22_40
Theory : list_1
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