Nuprl Lemma : filter-commutes
∀[T:Type]. ∀[P1,P2:T ⟶ 𝔹]. ∀[L:T List].  (filter(P1;filter(P2;L)) ~ filter(P2;filter(P1;L)))
Proof
Definitions occuring in Statement : 
filter: filter(P;l)
, 
list: T List
, 
bool: 𝔹
, 
uall: ∀[x:A]. B[x]
, 
function: x:A ⟶ B[x]
, 
universe: Type
, 
sqequal: s ~ t
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
Lemmas referenced : 
swap-filter-filter, 
list_wf, 
bool_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
sqequalAxiom, 
sqequalRule, 
isect_memberEquality, 
because_Cache, 
functionEquality, 
universeEquality
Latex:
\mforall{}[T:Type].  \mforall{}[P1,P2:T  {}\mrightarrow{}  \mBbbB{}].  \mforall{}[L:T  List].    (filter(P1;filter(P2;L))  \msim{}  filter(P2;filter(P1;L)))
Date html generated:
2016_05_15-PM-03_40_17
Last ObjectModification:
2015_12_27-PM-01_16_42
Theory : general
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