Nuprl Lemma : cons_iseg
∀[T:Type]. ∀a,b:T. ∀l1,l2:T List.  ([a / l1] ≤ [b / l2] 
⇐⇒ (a = b ∈ T) ∧ l1 ≤ l2)
Proof
Definitions occuring in Statement : 
iseg: l1 ≤ l2
, 
cons: [a / b]
, 
list: T List
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
true: True
, 
listp: A List+
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
false: False
, 
le: A ≤ B
, 
not: ¬A
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
append: as @ bs
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
top: Top
, 
so_apply: x[s1;s2;s3]
, 
squash: ↓T
, 
uimplies: b supposing a
, 
ge: i ≥ j 
, 
prop: ℙ
, 
subtype_rel: A ⊆r B
, 
iseg: l1 ≤ l2
, 
uall: ∀[x:A]. B[x]
, 
all: ∀x:A. B[x]
, 
iff: P 
⇐⇒ Q
, 
and: P ∧ Q
, 
implies: P 
⇒ Q
, 
exists: ∃x:A. B[x]
, 
member: t ∈ T
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
istype-void, 
true_wf, 
tl_wf, 
reduce_tl_cons_lemma, 
equal_wf, 
length_of_cons_lemma, 
non_neg_length, 
decidable__lt, 
full-omega-unsat, 
intformand_wf, 
intformnot_wf, 
intformless_wf, 
itermConstant_wf, 
itermAdd_wf, 
itermVar_wf, 
intformle_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_less_lemma, 
int_term_value_constant_lemma, 
int_term_value_add_lemma, 
int_term_value_var_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_wf, 
less_than_wf, 
list_ind_cons_lemma, 
reduce_hd_cons_lemma, 
hd_wf, 
squash_wf, 
ge_wf, 
length_wf, 
length_cons_ge_one, 
subtype_rel_list, 
top_wf, 
cons_wf, 
append_wf, 
list_wf
Rules used in proof : 
Error :isect_memberEquality_alt, 
Error :lambdaEquality_alt, 
Error :dependent_pairFormation_alt, 
hyp_replacement, 
applyLambdaEquality, 
setElimination, 
rename, 
dependent_set_memberEquality, 
addEquality, 
unionElimination, 
approximateComputation, 
independent_functionElimination, 
dependent_pairFormation, 
int_eqEquality, 
intEquality, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
applyEquality, 
lambdaEquality, 
imageElimination, 
independent_isectElimination, 
equalityTransitivity, 
equalitySymmetry, 
natural_numberEquality, 
cumulativity, 
because_Cache, 
imageMemberEquality, 
baseClosed, 
sqequalSubstitution, 
sqequalRule, 
sqequalReflexivity, 
sqequalTransitivity, 
computationStep, 
Error :isect_memberFormation_alt, 
Error :lambdaFormation_alt, 
independent_pairFormation, 
cut, 
sqequalHypSubstitution, 
productElimination, 
thin, 
hypothesis, 
Error :productIsType, 
Error :inhabitedIsType, 
hypothesisEquality, 
Error :equalityIsType1, 
introduction, 
extract_by_obid, 
isectElimination, 
Error :universeIsType, 
universeEquality
Latex:
\mforall{}[T:Type].  \mforall{}a,b:T.  \mforall{}l1,l2:T  List.    ([a  /  l1]  \mleq{}  [b  /  l2]  \mLeftarrow{}{}\mRightarrow{}  (a  =  b)  \mwedge{}  l1  \mleq{}  l2)
Date html generated:
2019_06_20-PM-02_12_50
Last ObjectModification:
2019_06_20-PM-02_08_37
Theory : list_1
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