Nuprl Lemma : l_before_append_iff
∀[T:Type]. ∀A,B:T List. ∀x,y:T.  (x before y ∈ A @ B 
⇐⇒ x before y ∈ A ∨ x before y ∈ B ∨ ((x ∈ A) ∧ (y ∈ B)))
Proof
Definitions occuring in Statement : 
l_before: x before y ∈ l
, 
l_member: (x ∈ l)
, 
append: as @ bs
, 
list: T List
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
, 
and: P ∧ Q
, 
universe: Type
Definitions unfolded in proof : 
rev_implies: P 
⇐ Q
, 
iff: P 
⇐⇒ Q
, 
implies: P 
⇒ Q
, 
so_apply: x[s]
, 
and: P ∧ Q
, 
or: P ∨ Q
, 
prop: ℙ
, 
so_lambda: λ2x.t[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
, 
uall: ∀[x:A]. B[x]
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
top: Top
, 
so_apply: x[s1;s2;s3]
, 
guard: {T}
, 
uimplies: b supposing a
, 
not: ¬A
, 
false: False
, 
cand: A c∧ B
Lemmas referenced : 
istype-universe, 
l_member_wf, 
append_wf, 
l_before_wf, 
iff_wf, 
list_wf, 
list_induction, 
list_ind_nil_lemma, 
nil_wf, 
or_wf, 
null_nil_lemma, 
btrue_wf, 
member-implies-null-eq-bfalse, 
btrue_neq_bfalse, 
nil_before, 
cons_wf, 
list_ind_cons_lemma, 
istype-void, 
cons_before, 
cons_member, 
member_append
Rules used in proof : 
universeEquality, 
instantiate, 
dependent_functionElimination, 
unionIsType, 
productIsType, 
because_Cache, 
functionIsType, 
rename, 
independent_functionElimination, 
universeIsType, 
productEquality, 
unionEquality, 
hypothesis, 
functionEquality, 
lambdaEquality_alt, 
sqequalRule, 
hypothesisEquality, 
isectElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
thin, 
cut, 
lambdaFormation_alt, 
isect_memberFormation_alt, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
lambdaFormation, 
independent_pairFormation, 
inrFormation, 
inlFormation, 
cumulativity, 
unionElimination, 
productElimination, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
inhabitedIsType, 
equalityIstype, 
isect_memberEquality_alt, 
inlFormation_alt, 
inrFormation_alt, 
promote_hyp
Latex:
\mforall{}[T:Type]
    \mforall{}A,B:T  List.  \mforall{}x,y:T.
        (x  before  y  \mmember{}  A  @  B  \mLeftarrow{}{}\mRightarrow{}  x  before  y  \mmember{}  A  \mvee{}  x  before  y  \mmember{}  B  \mvee{}  ((x  \mmember{}  A)  \mwedge{}  (y  \mmember{}  B)))
Date html generated:
2019_10_15-AM-10_21_41
Last ObjectModification:
2019_08_05-PM-02_08_48
Theory : list_1
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