Nuprl Lemma : l_before_l_index_le
∀[T:Type]
  ∀dT:EqDecider(T). ∀L:T List. ∀x,y:T.
    ((x ∈ L) 
⇒ (y ∈ L) 
⇒ x before y ∈ L ∨ (x = y ∈ T) supposing index(L;x) ≤ index(L;y))
Proof
Definitions occuring in Statement : 
l_index: index(L;x)
, 
l_before: x before y ∈ l
, 
l_member: (x ∈ l)
, 
list: T List
, 
deq: EqDecider(T)
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
le: A ≤ B
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
or: P ∨ Q
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
implies: P 
⇒ Q
, 
uimplies: b supposing a
, 
member: t ∈ T
, 
le: A ≤ B
, 
and: P ∧ Q
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
subtype_rel: A ⊆r B
, 
int_seg: {i..j-}
, 
prop: ℙ
, 
squash: ↓T
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
false: False
, 
top: Top
, 
cand: A c∧ B
, 
ge: i ≥ j 
, 
guard: {T}
, 
nat: ℕ
, 
lelt: i ≤ j < k
, 
true: True
, 
iff: P 
⇐⇒ Q
Lemmas referenced : 
le_witness_for_triv, 
decidable__lt, 
istype-le, 
l_index_wf, 
l_member_wf, 
list_wf, 
deq_wf, 
istype-universe, 
l_before_l_index, 
l_before_wf, 
select_wf, 
squash_wf, 
le_wf, 
less_than_wf, 
length_wf, 
istype-int, 
decidable__equal_int, 
full-omega-unsat, 
intformand_wf, 
intformnot_wf, 
intformeq_wf, 
itermVar_wf, 
intformless_wf, 
intformle_wf, 
int_formula_prop_and_lemma, 
istype-void, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_var_lemma, 
int_formula_prop_less_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_wf, 
non_neg_length, 
decidable__le, 
length_wf_nat, 
int_seg_properties, 
nat_properties, 
itermConstant_wf, 
int_term_value_constant_lemma, 
equal_wf, 
true_wf, 
select_l_index, 
subtype_rel_self, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
Error :lambdaFormation_alt, 
cut, 
introduction, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
productElimination, 
equalityTransitivity, 
hypothesis, 
equalitySymmetry, 
independent_isectElimination, 
rename, 
dependent_functionElimination, 
because_Cache, 
unionElimination, 
hypothesisEquality, 
applyEquality, 
Error :lambdaEquality_alt, 
setElimination, 
Error :inhabitedIsType, 
sqequalRule, 
Error :universeIsType, 
instantiate, 
universeEquality, 
Error :inlFormation_alt, 
independent_functionElimination, 
Error :equalityIstype, 
Error :inrFormation_alt, 
imageElimination, 
productEquality, 
natural_numberEquality, 
approximateComputation, 
Error :dependent_pairFormation_alt, 
int_eqEquality, 
Error :isect_memberEquality_alt, 
voidElimination, 
independent_pairFormation, 
applyLambdaEquality, 
imageMemberEquality, 
baseClosed
Latex:
\mforall{}[T:Type]
    \mforall{}dT:EqDecider(T).  \mforall{}L:T  List.  \mforall{}x,y:T.
        ((x  \mmember{}  L)  {}\mRightarrow{}  (y  \mmember{}  L)  {}\mRightarrow{}  x  before  y  \mmember{}  L  \mvee{}  (x  =  y)  supposing  index(L;x)  \mleq{}  index(L;y))
Date html generated:
2019_06_20-PM-01_56_56
Last ObjectModification:
2019_01_13-PM-02_23_43
Theory : decidable!equality
Home
Index