Nuprl Lemma : l_intersection-size
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[a,b,c:T List].
  (no_repeats(T;a) ⇒ no_repeats(T;b) ⇒ a ⊆ c ⇒ b ⊆ c ⇒ ((||a|| + ||b||) ≤ (||c|| + ||(a ⋂ b)||)))
Proof
Definitions occuring in Statement : 
l_intersection: (L1 ⋂ L2), 
l_contains: A ⊆ B, 
no_repeats: no_repeats(T;l), 
length: ||as||, 
list: T List, 
deq: EqDecider(T), 
uall: ∀[x:A]. B[x], 
le: A ≤ B, 
implies: P ⇒ Q, 
add: n + m, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
implies: P ⇒ Q, 
l_intersection: (L1 ⋂ L2), 
uimplies: b supposing a, 
l_contains: A ⊆ B, 
l_member: (x ∈ l), 
l_all: (∀x∈L.P[x]), 
exists: ∃x:A. B[x], 
int_seg: {i..j-}, 
subtype_rel: A ⊆r B, 
lelt: i ≤ j < k, 
and: P ∧ Q, 
ge: i ≥ j , 
guard: {T}, 
all: ∀x:A. B[x], 
prop: ℙ, 
decidable: Dec(P), 
or: P ∨ Q, 
false: False, 
nat: ℕ, 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
top: Top, 
less_than: a < b, 
squash: ↓T, 
le: A ≤ B, 
cand: A c∧ B, 
pi1: fst(t), 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
uiff: uiff(P;Q), 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
sq_type: SQType(T), 
bnot: ¬bb, 
assert: ↑b, 
inject: Inj(A;B;f), 
no_repeats: no_repeats(T;l), 
less_than': less_than'(a;b), 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
true: True, 
label: ...$L... t
Lemmas referenced : 
no_repeats_filter, 
non_neg_length, 
int_seg_properties, 
length_wf, 
decidable__le, 
lelt_wf, 
length_wf_nat, 
nat_properties, 
full-omega-unsat, 
istype-int, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_not_lemma, 
int_seg_wf, 
select_wf, 
decidable__lt, 
int_formula_prop_less_lemma, 
no_repeats_l_index-inj, 
l_intersection_wf, 
l_contains_wf, 
no_repeats_wf, 
le_witness_for_triv, 
list_wf, 
deq_wf, 
less_than_wf, 
nat_wf, 
member-intersection, 
select_member, 
l_index_wf, 
l_member_wf, 
pigeon-hole, 
add_nat_wf, 
add-is-int-iff, 
int_term_value_add_lemma, 
int_formula_prop_eq_lemma, 
false_wf, 
le_wf, 
lt_int_wf, 
eqtt_to_assert, 
assert_of_lt_int, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_wf, 
bool_subtype_base, 
assert-bnot, 
iff_weakening_uiff, 
assert_wf, 
subtract_wf, 
intformand_wf, 
intformnot_wf, 
intformle_wf, 
itermConstant_wf, 
itermSubtract_wf, 
itermVar_wf, 
intformless_wf, 
int_term_value_subtract_lemma, 
int_formula_prop_wf, 
itermAdd_wf, 
deq-member_wf, 
assert-deq-member, 
add-member-int_seg1, 
intformeq_wf, 
decidable__equal_int_seg, 
int_seg_subtype_nat, 
set_subtype_base, 
int_subtype_base, 
equal_wf, 
squash_wf, 
true_wf, 
subtype_rel_self, 
iff_weakening_equal, 
not_wf, 
decidable__equal_int
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
Error :lambdaFormation_alt, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
because_Cache, 
independent_isectElimination, 
hypothesis, 
sqequalRule, 
promote_hyp, 
productElimination, 
Error :dependent_pairFormation_alt, 
hypothesisEquality, 
Error :functionExtensionality_alt, 
Error :dependent_set_memberEquality_alt, 
applyEquality, 
independent_pairFormation, 
natural_numberEquality, 
setElimination, 
rename, 
dependent_functionElimination, 
Error :universeIsType, 
unionElimination, 
equalityTransitivity, 
equalitySymmetry, 
applyLambdaEquality, 
independent_functionElimination, 
voidElimination, 
approximateComputation, 
Error :lambdaEquality_alt, 
int_eqEquality, 
Error :isect_memberEquality_alt, 
Error :functionIsType, 
Error :equalityIsType1, 
imageElimination, 
functionExtensionality, 
cumulativity, 
Error :inhabitedIsType, 
universeEquality, 
Error :productIsType, 
addEquality, 
pointwiseFunctionality, 
baseApply, 
closedConclusion, 
baseClosed, 
equalityElimination, 
instantiate, 
hyp_replacement, 
Error :equalityIsType4, 
intEquality, 
imageMemberEquality, 
productEquality, 
Error :equalityIsType3, 
Error :equalityIsType2
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[a,b,c:T  List].
    (no\_repeats(T;a)
    {}\mRightarrow{}  no\_repeats(T;b)
    {}\mRightarrow{}  a  \msubseteq{}  c
    {}\mRightarrow{}  b  \msubseteq{}  c
    {}\mRightarrow{}  ((||a||  +  ||b||)  \mleq{}  (||c||  +  ||(a  \mcap{}  b)||)))
Date html generated:
2019_06_20-PM-01_58_00
Last ObjectModification:
2018_10_03-PM-10_28_04
Theory : decidable!equality
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