Nuprl Lemma : set-equal-cons
∀[T:Type]
  ∀u:T. ∀v,bs:T List.
    (set-equal(T;[u / v];bs) 
⇐⇒ ∃cs,ds:T List. ((bs = (cs @ [u / ds]) ∈ (T List)) ∧ set-equal(T;v;cs @ ds))) supposing 
       (no_repeats(T;bs) and 
       no_repeats(T;[u / v]))
Proof
Definitions occuring in Statement : 
set-equal: set-equal(T;x;y)
, 
no_repeats: no_repeats(T;l)
, 
append: as @ bs
, 
cons: [a / b]
, 
list: T List
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
exists: ∃x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
uimplies: b supposing a
, 
member: t ∈ T
, 
implies: P 
⇒ Q
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
prop: ℙ
, 
rev_implies: P 
⇐ Q
, 
so_lambda: λ2x.t[x]
, 
top: Top
, 
so_apply: x[s]
, 
set-equal: set-equal(T;x;y)
, 
or: P ∨ Q
, 
exists: ∃x:A. B[x]
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
so_apply: x[s1;s2;s3]
, 
cand: A c∧ B
, 
guard: {T}
, 
uiff: uiff(P;Q)
, 
not: ¬A
, 
false: False
Lemmas referenced : 
no_repeats_witness, 
cons_wf, 
set-equal_wf, 
exists_wf, 
list_wf, 
equal_wf, 
append_wf, 
length_wf, 
length-append, 
no_repeats_wf, 
cons_member, 
l_member_wf, 
l_member_decomp, 
list_ind_cons_lemma, 
list_ind_nil_lemma, 
member_append, 
or_wf, 
iff_wf, 
no_repeats_cons, 
no_repeats-append, 
l_disjoint_cons, 
length_wf_nat, 
nat_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
cumulativity, 
hypothesis, 
independent_functionElimination, 
rename, 
because_Cache, 
independent_pairFormation, 
sqequalRule, 
lambdaEquality, 
productEquality, 
applyLambdaEquality, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
universeEquality, 
dependent_functionElimination, 
productElimination, 
inlFormation, 
dependent_pairFormation, 
equalitySymmetry, 
hyp_replacement, 
promote_hyp, 
addLevel, 
orFunctionality, 
impliesFunctionality, 
inrFormation, 
unionElimination, 
independent_isectElimination, 
dependent_set_memberEquality, 
setElimination
Latex:
\mforall{}[T:Type]
    \mforall{}u:T.  \mforall{}v,bs:T  List.
        (set-equal(T;[u  /  v];bs)
              \mLeftarrow{}{}\mRightarrow{}  \mexists{}cs,ds:T  List.  ((bs  =  (cs  @  [u  /  ds]))  \mwedge{}  set-equal(T;v;cs  @  ds)))  supposing 
              (no\_repeats(T;bs)  and 
              no\_repeats(T;[u  /  v]))
Date html generated:
2017_04_17-AM-07_37_04
Last ObjectModification:
2017_02_27-PM-04_12_23
Theory : list_1
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