Nuprl Lemma : iseg_append_length
∀[T:Type]. ∀l1,l2,l3:T List.  (l1 ≤ l2 @ l3 ⇒ l1 ≤ l2 supposing ||l1|| ≤ ||l2||)
Proof
Definitions occuring in Statement : 
iseg: l1 ≤ l2, 
length: ||as||, 
append: as @ bs, 
list: T List, 
uimplies: b supposing a, 
uall: ∀[x:A]. B[x], 
le: A ≤ B, 
all: ∀x:A. B[x], 
implies: P ⇒ Q, 
universe: Type
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, 
not: ¬A, 
false: False, 
prop: ℙ, 
iff: P ⇐⇒ Q, 
or: P ∨ Q, 
exists: ∃x:A. B[x], 
squash: ↓T, 
subtype_rel: A ⊆r B, 
top: Top, 
true: True, 
guard: {T}, 
less_than: a < b, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
Lemmas referenced : 
less_than'_wf, 
length_wf, 
iseg_append_iff, 
equal_wf, 
squash_wf, 
true_wf, 
length_append, 
subtype_rel_list, 
top_wf, 
iff_weakening_equal, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformeq_wf, 
itermVar_wf, 
itermAdd_wf, 
intformle_wf, 
intformless_wf, 
itermConstant_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_var_lemma, 
int_term_value_add_lemma, 
int_formula_prop_le_lemma, 
int_formula_prop_less_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_wf, 
le_wf, 
iseg_wf, 
append_wf, 
list_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
lambdaFormation, 
cut, 
introduction, 
sqequalRule, 
sqequalHypSubstitution, 
productElimination, 
thin, 
independent_pairEquality, 
lambdaEquality, 
dependent_functionElimination, 
hypothesisEquality, 
voidElimination, 
extract_by_obid, 
isectElimination, 
cumulativity, 
hypothesis, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
rename, 
independent_functionElimination, 
unionElimination, 
applyLambdaEquality, 
applyEquality, 
imageElimination, 
because_Cache, 
intEquality, 
independent_isectElimination, 
isect_memberEquality, 
voidEquality, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
universeEquality, 
dependent_pairFormation, 
int_eqEquality, 
independent_pairFormation, 
computeAll
Latex:
\mforall{}[T:Type].  \mforall{}l1,l2,l3:T  List.    (l1  \mleq{}  l2  @  l3  {}\mRightarrow{}  l1  \mleq{}  l2  supposing  ||l1||  \mleq{}  ||l2||)
Date html generated:
2017_04_17-AM-08_46_35
Last ObjectModification:
2017_02_27-PM-05_03_42
Theory : list_1
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