Nuprl Lemma : fset-size-union
∀[T:Type]
  ∀[eq:EqDecider(T)]. ∀[a,b:fset(T)].  (||a ⋃ b|| = ((||a|| + ||b||) - ||a ⋂ b||) ∈ ℤ) supposing valueall-type(T)
Proof
Definitions occuring in Statement : 
fset-size: ||s||, 
fset-intersection: a ⋂ b, 
fset-union: x ⋃ y, 
fset: fset(T), 
deq: EqDecider(T), 
valueall-type: valueall-type(T), 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x], 
subtract: n - m, 
add: n + m, 
int: ℤ, 
universe: Type, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x], 
member: t ∈ T, 
uimplies: b supposing a, 
all: ∀x:A. B[x], 
so_lambda: λ2x.t[x], 
subtype_rel: A ⊆r B, 
nat: ℕ, 
so_apply: x[s], 
implies: P ⇒ Q, 
prop: ℙ, 
guard: {T}, 
squash: ↓T, 
true: True, 
iff: P ⇐⇒ Q, 
and: P ∧ Q, 
rev_implies: P ⇐ Q, 
top: Top, 
decidable: Dec(P), 
or: P ∨ Q, 
satisfiable_int_formula: satisfiable_int_formula(fmla), 
exists: ∃x:A. B[x], 
false: False, 
not: ¬A, 
uiff: uiff(P;Q), 
sq_stable: SqStable(P), 
cand: A c∧ B
Lemmas referenced : 
fset-induction, 
all_wf, 
fset_wf, 
equal_wf, 
fset-size_wf, 
fset-union_wf, 
subtract_wf, 
fset-intersection_wf, 
nat_wf, 
sq_stable__all, 
sq_stable__equal, 
not_wf, 
fset-member_wf, 
deq_wf, 
valueall-type_wf, 
squash_wf, 
true_wf, 
empty-fset-union, 
iff_weakening_equal, 
fsize_empty_lemma, 
empty_intersect_lemma, 
decidable__equal_int, 
satisfiable-full-omega-tt, 
intformnot_wf, 
intformeq_wf, 
itermVar_wf, 
itermSubtract_wf, 
itermAdd_wf, 
itermConstant_wf, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_var_lemma, 
int_term_value_subtract_lemma, 
int_term_value_add_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_wf, 
empty-fset_wf, 
fset-add_wf, 
fset-add-as-cons, 
fset-add-union, 
decidable__fset-member, 
and_wf, 
fset-extensionality, 
sq_stable_from_decidable, 
decidable__or, 
or_wf, 
member-fset-union, 
fset-member_witness, 
uiff_wf, 
member-fset-add, 
decidable-equal-deq, 
decidable__and2, 
iff_weakening_uiff, 
member-fset-intersection, 
subtract-is-int-iff, 
add-is-int-iff, 
intformand_wf, 
int_formula_prop_and_lemma, 
false_wf, 
add_functionality_wrt_eq, 
fset-size-add
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
thin, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
dependent_functionElimination, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
intEquality, 
because_Cache, 
applyEquality, 
addEquality, 
setElimination, 
rename, 
independent_functionElimination, 
lambdaFormation, 
axiomEquality, 
isect_memberEquality, 
equalityTransitivity, 
equalitySymmetry, 
universeEquality, 
imageElimination, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_isectElimination, 
productElimination, 
voidElimination, 
voidEquality, 
unionElimination, 
dependent_pairFormation, 
int_eqEquality, 
computeAll, 
hyp_replacement, 
applyLambdaEquality, 
inrFormation, 
dependent_set_memberEquality, 
independent_pairFormation, 
addLevel, 
orFunctionality, 
independent_pairEquality, 
productEquality, 
inlFormation, 
pointwiseFunctionality, 
promote_hyp, 
baseApply, 
closedConclusion, 
impliesFunctionality
Latex:
\mforall{}[T:Type]
    \mforall{}[eq:EqDecider(T)].  \mforall{}[a,b:fset(T)].    (||a  \mcup{}  b||  =  ((||a||  +  ||b||)  -  ||a  \mcap{}  b||)) 
    supposing  valueall-type(T)
Date html generated:
2017_04_17-AM-09_22_54
Last ObjectModification:
2017_02_27-PM-05_25_17
Theory : finite!sets
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