Nuprl Lemma : fset-add-remove
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[s:fset(T)]. ∀[x:T].  fset-add(eq;x;fset-remove(eq;x;s)) = s ∈ fset(T) supposing x ∈ s
Proof
Definitions occuring in Statement : 
fset-add: fset-add(eq;x;s)
, 
fset-remove: fset-remove(eq;y;s)
, 
fset-member: a ∈ s
, 
fset: fset(T)
, 
deq: EqDecider(T)
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uimplies: b supposing a
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
prop: ℙ
, 
or: P ∨ Q
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
, 
decidable: Dec(P)
, 
guard: {T}
, 
cand: A c∧ B
, 
deq: EqDecider(T)
Lemmas referenced : 
fset-extensionality, 
fset-add_wf, 
fset-remove_wf, 
fset-member_witness, 
or_wf, 
equal_wf, 
fset-member_wf, 
not_wf, 
member-fset-remove, 
uiff_wf, 
member-fset-add, 
fset_wf, 
deq_wf, 
and_wf, 
deq_property, 
assert_wf, 
decidable__assert, 
decidable_functionality, 
iff_weakening_uiff
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
because_Cache, 
hypothesisEquality, 
cumulativity, 
hypothesis, 
productElimination, 
independent_isectElimination, 
independent_pairFormation, 
independent_functionElimination, 
productEquality, 
rename, 
addLevel, 
orFunctionality, 
dependent_functionElimination, 
sqequalRule, 
independent_pairEquality, 
isect_memberEquality, 
equalityTransitivity, 
equalitySymmetry, 
axiomEquality, 
universeEquality, 
unionElimination, 
dependent_set_memberEquality, 
applyEquality, 
lambdaEquality, 
setElimination, 
setEquality, 
hyp_replacement, 
Error :applyLambdaEquality, 
inlFormation, 
inrFormation
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[s:fset(T)].  \mforall{}[x:T].
    fset-add(eq;x;fset-remove(eq;x;s))  =  s  supposing  x  \mmember{}  s
Date html generated:
2016_10_21-AM-10_44_15
Last ObjectModification:
2016_07_12-AM-05_51_07
Theory : finite!sets
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