Nuprl Lemma : bag-remove1-append1
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[x,y:T]. ∀[bs:bag(T)].
  (bag-remove1(eq;{y} + bs;x)
  = if eq x y then inl bs else case bag-remove1(eq;bs;x) of inl(as) => inl ({y} + as) | inr(x) => inr ⋅  fi 
  ∈ (bag(T)?))
Proof
Definitions occuring in Statement : 
bag-remove1: bag-remove1(eq;bs;a), 
bag-append: as + bs, 
single-bag: {x}, 
bag: bag(T), 
deq: EqDecider(T), 
ifthenelse: if b then t else f fi , 
it: ⋅, 
uall: ∀[x:A]. B[x], 
unit: Unit, 
apply: f a, 
decide: case b of inl(x) => s[x] | inr(y) => t[y], 
inr: inr x , 
inl: inl x, 
union: left + right, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
deq: EqDecider(T), 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
exposed-bfalse: exposed-bfalse, 
bool: 𝔹, 
unit: Unit, 
it: ⋅, 
btrue: tt, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
eqof: eqof(d), 
ifthenelse: if b then t else f fi , 
squash: ↓T, 
true: True, 
subtype_rel: A ⊆r B, 
guard: {T}, 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
bfalse: ff, 
exists: ∃x:A. B[x], 
or: P ∨ Q, 
sq_type: SQType(T), 
bnot: ¬bb, 
assert: ↑b, 
false: False, 
not: ¬A, 
prop: ℙ, 
isl: isl(x), 
sq_or: a ↓∨ b
Lemmas referenced : 
eqtt_to_assert, 
safe-assert-deq, 
equal_wf, 
bag_wf, 
unit_wf2, 
bag-remove1_wf, 
bag-append_wf, 
single-bag_wf, 
iff_weakening_equal, 
bag-remove1-member, 
eqff_to_assert, 
bool_cases_sqequal, 
subtype_base_sq, 
bool_subtype_base, 
assert-bnot, 
iff_weakening_uiff, 
assert_wf, 
bag-remove1-property, 
squash_wf, 
true_wf, 
istype-universe, 
inl-one-one, 
not-0-eq-1, 
inr-one-one, 
it_wf, 
subtype_rel_self, 
btrue_wf, 
bfalse_wf, 
btrue_neq_bfalse, 
bag-append-assoc-comm, 
bag-append-cancel, 
bag-member-single, 
bag-member_wf, 
bag-member-append
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation_alt, 
introduction, 
cut, 
applyEquality, 
sqequalHypSubstitution, 
setElimination, 
thin, 
rename, 
hypothesisEquality, 
hypothesis, 
inhabitedIsType, 
lambdaFormation_alt, 
unionElimination, 
equalityElimination, 
extract_by_obid, 
isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
productElimination, 
independent_isectElimination, 
sqequalRule, 
lambdaEquality_alt, 
imageElimination, 
because_Cache, 
universeIsType, 
universeEquality, 
unionEquality, 
dependent_functionElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
inlEquality_alt, 
independent_functionElimination, 
dependent_pairFormation_alt, 
equalityIsType3, 
promote_hyp, 
instantiate, 
voidElimination, 
equalityIsType1, 
isect_memberEquality_alt, 
axiomEquality, 
isectIsTypeImplies, 
applyLambdaEquality, 
inrEquality_alt, 
dependent_set_memberEquality_alt, 
independent_pairFormation, 
productIsType, 
inrFormation_alt, 
inlFormation_alt
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[x,y:T].  \mforall{}[bs:bag(T)].
    (bag-remove1(eq;\{y\}  +  bs;x)
    =  if  eq  x  y
        then  inl  bs
        else  case  bag-remove1(eq;bs;x)  of  inl(as)  =>  inl  (\{y\}  +  as)  |  inr(x)  =>  inr  \mcdot{} 
        fi  )
Date html generated:
2019_10_16-AM-11_31_08
Last ObjectModification:
2018_10_16-AM-09_34_29
Theory : bags_2
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