Nuprl Lemma : empty-bag-iff-size
∀[T:Type]. ∀[bs:bag(T)].  uiff(bs = {} ∈ bag(T);#(bs) ≤ 0)
Proof
Definitions occuring in Statement : 
bag-size: #(bs), 
empty-bag: {}, 
bag: bag(T), 
uiff: uiff(P;Q), 
uall: ∀[x:A]. B[x], 
le: A ≤ B, 
natural_number: $n, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uiff: uiff(P;Q), 
and: P ∧ Q, 
uimplies: b supposing a, 
le: A ≤ B, 
not: ¬A, 
implies: P ⇒ Q, 
false: False, 
prop: ℙ, 
subtype_rel: A ⊆r B, 
nat: ℕ, 
so_lambda: λ2x.t[x], 
so_apply: x[s], 
iff: P ⇐⇒ Q, 
rev_implies: P ⇐ Q, 
all: ∀x:A. B[x], 
decidable: Dec(P), 
or: P ∨ Q, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
top: Top, 
squash: ↓T, 
guard: {T}, 
less_than: a < b
Lemmas referenced : 
bag_wf, 
less_than'_wf, 
bag-size_wf, 
nat_wf, 
equal-wf-T-base, 
le_wf, 
iff_weakening_uiff, 
all_wf, 
not_wf, 
bag-member_wf, 
empty-bag-iff-no-member, 
uiff_wf, 
decidable__le, 
decidable__lt, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformless_wf, 
itermConstant_wf, 
itermVar_wf, 
intformle_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_less_lemma, 
int_term_value_constant_lemma, 
int_term_value_var_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_wf, 
bag-member-iff-size
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
sqequalRule, 
sqequalHypSubstitution, 
productElimination, 
thin, 
independent_pairEquality, 
isect_memberEquality, 
isectElimination, 
hypothesisEquality, 
lambdaEquality, 
dependent_functionElimination, 
because_Cache, 
axiomEquality, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
extract_by_obid, 
cumulativity, 
voidElimination, 
natural_numberEquality, 
applyEquality, 
setElimination, 
rename, 
baseClosed, 
universeEquality, 
addLevel, 
independent_pairFormation, 
independent_isectElimination, 
independent_functionElimination, 
instantiate, 
lambdaFormation, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
voidEquality, 
computeAll, 
imageElimination, 
imageMemberEquality
Latex:
\mforall{}[T:Type].  \mforall{}[bs:bag(T)].    uiff(bs  =  \{\};\#(bs)  \mleq{}  0)
Date html generated:
2017_10_01-AM-08_53_26
Last ObjectModification:
2017_07_26-PM-04_35_07
Theory : bags
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