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Step * of Lemma length-mapfilter

∀[l,f,P:Top].  (||mapfilter(f;P;l)|| ~ ||filter(P;l)||)
BY
{ ((UnivCD THENA Auto) THEN RepUR ``mapfilter`` 0 THEN RWO "map-length" 0 THEN Auto) }

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Latex:

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Latex:
\mforall{}[l,f,P:Top].    (||mapfilter(f;P;l)||  \msim{}  ||filter(P;l)||)


By

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Latex:
((UnivCD  THENA  Auto)  THEN  RepUR  ``mapfilter``  0  THEN  RWO  "map-length"  0  THEN  Auto)

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