Nuprl Lemma : bag-drop-append
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[x:T]. ∀[bs,cs:bag(T)].
  (bag-drop(eq;bs + cs;x) = if ((#x in bs) =z 0) then bs + bag-drop(eq;cs;x) else bag-drop(eq;bs;x) + cs fi  ∈ bag(T))
Proof
Definitions occuring in Statement : 
bag-drop: bag-drop(eq;bs;a), 
bag-count: (#x in bs), 
bag-append: as + bs, 
bag: bag(T), 
deq: EqDecider(T), 
ifthenelse: if b then t else f fi , 
eq_int: (i =z j), 
uall: ∀[x:A]. B[x], 
natural_number: $n, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
all: ∀x:A. B[x], 
or: P ∨ Q, 
and: P ∧ Q, 
subtype_rel: A ⊆r B, 
nat: ℕ, 
uiff: uiff(P;Q), 
uimplies: b supposing a, 
squash: ↓T, 
prop: ℙ, 
true: True, 
guard: {T}, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
implies: P ⇒ Q, 
sq_or: a ↓∨ b, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
ifthenelse: if b then t else f fi , 
bfalse: ff, 
exists: ∃x:A. B[x], 
sq_type: SQType(T), 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
not: ¬A, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
top: Top, 
nequal: a ≠ b ∈ T , 
decidable: Dec(P), 
ge: i ≥ j , 
eq_int: (i =z j), 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
le: A ≤ B, 
less_than': less_than'(a;b), 
rev_uimplies: rev_uimplies(P;Q)
Lemmas referenced : 
bag-drop-property, 
bag-append_wf, 
bag_wf, 
bag-append-cancel, 
single-bag_wf, 
bag-drop_wf, 
ifthenelse_wf, 
eq_int_wf, 
bag-count_wf, 
nat_wf, 
bag-member_wf, 
squash_wf, 
true_wf, 
subtype_rel_self, 
iff_weakening_equal, 
bag-member-append, 
bag-member-single, 
bool_wf, 
eqtt_to_assert, 
assert_of_eq_int, 
eqff_to_assert, 
equal_wf, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
neg_assert_of_eq_int, 
bag-member-count, 
full-omega-unsat, 
intformand_wf, 
intformle_wf, 
itermConstant_wf, 
itermVar_wf, 
intformeq_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_le_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_eq_lemma, 
int_formula_prop_wf, 
bag-append-assoc-comm, 
bag-append-assoc2, 
decidable__le, 
nat_properties, 
intformnot_wf, 
int_formula_prop_not_lemma, 
set_subtype_base, 
le_wf, 
int_subtype_base, 
decidable__equal_nat, 
false_wf, 
decidable__equal_int, 
equal-wf-T-base
Rules used in proof : 
cut, 
introduction, 
extract_by_obid, 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
hypothesis, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
dependent_functionElimination, 
unionElimination, 
productElimination, 
sqequalRule, 
isect_memberEquality, 
axiomEquality, 
because_Cache, 
universeEquality, 
equalityTransitivity, 
equalitySymmetry, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
natural_numberEquality, 
independent_isectElimination, 
imageElimination, 
imageMemberEquality, 
baseClosed, 
instantiate, 
independent_functionElimination, 
inlFormation, 
lambdaFormation, 
equalityElimination, 
dependent_pairFormation, 
promote_hyp, 
cumulativity, 
voidElimination, 
approximateComputation, 
int_eqEquality, 
intEquality, 
voidEquality, 
independent_pairFormation, 
applyLambdaEquality, 
dependent_set_memberEquality, 
inrFormation
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[x:T].  \mforall{}[bs,cs:bag(T)].
    (bag-drop(eq;bs  +  cs;x)
    =  if  ((\#x  in  bs)  =\msubz{}  0)  then  bs  +  bag-drop(eq;cs;x)  else  bag-drop(eq;bs;x)  +  cs  fi  )
Date html generated:
2018_05_21-PM-09_48_30
Last ObjectModification:
2018_05_19-PM-04_20_23
Theory : bags_2
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