Nuprl Lemma : list-index-cmp-zero
∀[T:Type]. ∀[eq:EqDecider(T)]. ∀[L:T List]. ∀[A:Type]. ∀[f:A ⟶ T]. ∀[x,y:{x:A| (f x ∈ L)} ].
  uiff((list-index-cmp(eq;L;f) x y) = 0 ∈ ℤ;(f x) = (f y) ∈ T)
Proof
Definitions occuring in Statement : 
list-index-cmp: list-index-cmp(eq;L;f)
, 
l_member: (x ∈ l)
, 
list: T List
, 
deq: EqDecider(T)
, 
uiff: uiff(P;Q)
, 
uall: ∀[x:A]. B[x]
, 
set: {x:A| B[x]} 
, 
apply: f a
, 
function: x:A ⟶ B[x]
, 
natural_number: $n
, 
int: ℤ
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
uimplies: b supposing a
, 
subtype_rel: A ⊆r B
, 
comparison: comparison(T)
, 
prop: ℙ
, 
int-minus-comparison: int-minus-comparison(f)
, 
list-index-cmp: list-index-cmp(eq;L;f)
, 
guard: {T}
, 
implies: P 
⇒ Q
, 
all: ∀x:A. B[x]
, 
sq_type: SQType(T)
, 
so_apply: x[s]
, 
so_lambda: λ2x.t[x]
, 
int_seg: {i..j-}
, 
squash: ↓T
, 
less_than: a < b
, 
top: Top
, 
not: ¬A
, 
false: False
, 
exists: ∃x:A. B[x]
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
or: P ∨ Q
, 
decidable: Dec(P)
, 
lelt: i ≤ j < k
, 
rev_implies: P 
⇐ Q
, 
iff: P 
⇐⇒ Q
, 
true: True
Lemmas referenced : 
list-index-cmp_wf, 
int_subtype_base, 
l_member_wf, 
list_wf, 
deq_wf, 
list-index-property, 
lelt_wf, 
set_subtype_base, 
length_wf, 
int_seg_wf, 
subtype_base_sq, 
subtract_wf, 
equal-wf-T-base, 
int_formula_prop_less_lemma, 
intformless_wf, 
decidable__lt, 
int_formula_prop_le_lemma, 
intformle_wf, 
decidable__le, 
int_formula_prop_wf, 
int_term_value_constant_lemma, 
int_term_value_subtract_lemma, 
int_term_value_var_lemma, 
int_formula_prop_eq_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_and_lemma, 
itermConstant_wf, 
itermSubtract_wf, 
itermVar_wf, 
intformeq_wf, 
intformnot_wf, 
intformand_wf, 
satisfiable-full-omega-tt, 
decidable__equal_int, 
int_seg_properties, 
equal_wf, 
isl-list-index, 
list-index_wf, 
top_wf, 
outl_wf, 
full-omega-unsat, 
istype-int, 
istype-void, 
squash_wf, 
true_wf, 
subtype_rel_self, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
independent_pairFormation, 
hypothesis, 
Error :equalityIsType4, 
Error :universeIsType, 
intEquality, 
applyEquality, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
Error :lambdaEquality_alt, 
setElimination, 
rename, 
Error :inhabitedIsType, 
equalityTransitivity, 
equalitySymmetry, 
sqequalRule, 
baseClosed, 
Error :equalityIsType1, 
productElimination, 
independent_pairEquality, 
Error :isect_memberEquality_alt, 
axiomEquality, 
Error :isectIsTypeImplies, 
Error :setIsType, 
Error :functionIsType, 
universeEquality, 
because_Cache, 
independent_isectElimination, 
cumulativity, 
functionExtensionality, 
independent_functionElimination, 
dependent_functionElimination, 
lambdaEquality, 
natural_numberEquality, 
instantiate, 
imageElimination, 
dependent_set_memberEquality, 
computeAll, 
voidEquality, 
voidElimination, 
isect_memberEquality, 
int_eqEquality, 
dependent_pairFormation, 
unionElimination, 
lambdaFormation, 
Error :dependent_set_memberEquality_alt, 
closedConclusion, 
Error :lambdaFormation_alt, 
applyLambdaEquality, 
approximateComputation, 
Error :dependent_pairFormation_alt, 
hyp_replacement, 
imageMemberEquality
Latex:
\mforall{}[T:Type].  \mforall{}[eq:EqDecider(T)].  \mforall{}[L:T  List].  \mforall{}[A:Type].  \mforall{}[f:A  {}\mrightarrow{}  T].  \mforall{}[x,y:\{x:A|  (f  x  \mmember{}  L)\}  ].
    uiff((list-index-cmp(eq;L;f)  x  y)  =  0;(f  x)  =  (f  y))
Date html generated:
2019_06_20-PM-01_56_41
Last ObjectModification:
2018_10_15-PM-02_32_50
Theory : decidable!equality
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