Nuprl Lemma : filter-union
∀[T:Type]. ∀eq:EqDecider(T). ∀as,bs:T List. ∀P:T ⟶ 𝔹.  (filter(P;as ⋃ bs) = filter(P;as) ⋃ filter(P;bs) ∈ (T List))
Proof
Definitions occuring in Statement : 
l-union: as ⋃ bs, 
filter: filter(P;l), 
list: T List, 
deq: EqDecider(T), 
bool: 𝔹, 
uall: ∀[x:A]. B[x], 
all: ∀x:A. B[x], 
function: x:A ⟶ B[x], 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x], 
l-union: as ⋃ bs, 
so_lambda: λ2x.t[x], 
subtype_rel: A ⊆r B, 
so_apply: x[s], 
prop: ℙ, 
uimplies: b supposing a, 
implies: P ⇒ Q, 
top: Top, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
exists: ∃x:A. B[x], 
or: P ∨ Q, 
sq_type: SQType(T), 
guard: {T}, 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
squash: ↓T, 
not: ¬A, 
iff: P ⇐⇒ Q, 
true: True, 
rev_implies: P ⇐ Q, 
cand: A c∧ B
Lemmas referenced : 
list_induction, 
equal_wf, 
list_wf, 
filter_wf5, 
reduce_wf, 
insert_wf, 
subtype_rel_dep_function, 
bool_wf, 
l_member_wf, 
subtype_rel_self, 
set_wf, 
reduce_nil_lemma, 
filter_nil_lemma, 
reduce_cons_lemma, 
filter_cons_lemma, 
eqtt_to_assert, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
deq_wf, 
insert-cases2, 
squash_wf, 
true_wf, 
ite_rw_false, 
cons_wf, 
member_filter_2, 
assert_wf, 
iff_weakening_equal, 
member_filter
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
lambdaFormation, 
thin, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
because_Cache, 
applyEquality, 
setEquality, 
independent_isectElimination, 
setElimination, 
rename, 
independent_functionElimination, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
functionExtensionality, 
unionElimination, 
equalityElimination, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
dependent_pairFormation, 
promote_hyp, 
instantiate, 
functionEquality, 
axiomEquality, 
universeEquality, 
hyp_replacement, 
applyLambdaEquality, 
imageElimination, 
equalityUniverse, 
levelHypothesis, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_pairFormation
Latex:
\mforall{}[T:Type]
    \mforall{}eq:EqDecider(T).  \mforall{}as,bs:T  List.  \mforall{}P:T  {}\mrightarrow{}  \mBbbB{}.    (filter(P;as  \mcup{}  bs)  =  filter(P;as)  \mcup{}  filter(P;bs))
Date html generated:
2017_04_17-AM-09_09_50
Last ObjectModification:
2017_02_27-PM-05_17_56
Theory : decidable!equality
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