Nuprl Lemma : length_zip
∀[T1,T2:Type]. ∀[as:T1 List]. ∀[bs:T2 List].  ||zip(as;bs)|| = ||as|| ∈ ℤ supposing ||as|| = ||bs|| ∈ ℤ
Proof
Definitions occuring in Statement : 
zip: zip(as;bs)
, 
length: ||as||
, 
list: T List
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
int: ℤ
, 
universe: Type
, 
equal: s = t ∈ T
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
so_lambda: λ2x.t[x]
, 
uimplies: b supposing a
, 
prop: ℙ
, 
so_apply: x[s]
, 
implies: P 
⇒ Q
, 
zip: zip(as;bs)
, 
list_ind: list_ind, 
nil: []
, 
it: ⋅
, 
all: ∀x:A. B[x]
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
top: Top
, 
so_apply: x[s1;s2;s3]
, 
squash: ↓T
, 
guard: {T}
, 
decidable: Dec(P)
, 
or: P ∨ Q
, 
false: False
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
satisfiable_int_formula: satisfiable_int_formula(fmla)
, 
exists: ∃x:A. B[x]
, 
not: ¬A
, 
true: True
, 
subtype_rel: A ⊆r B
, 
iff: P 
⇐⇒ Q
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
list_induction, 
uall_wf, 
list_wf, 
isect_wf, 
equal_wf, 
length_wf, 
zip_wf, 
equal-wf-base-T, 
equal-wf-T-base, 
nil_wf, 
length_of_nil_lemma, 
list_ind_nil_lemma, 
equal-wf-base, 
length_of_cons_lemma, 
cons_wf, 
list_ind_cons_lemma, 
squash_wf, 
true_wf, 
add_functionality_wrt_eq, 
decidable__equal_int, 
add-is-int-iff, 
satisfiable-full-omega-tt, 
intformand_wf, 
intformnot_wf, 
intformeq_wf, 
itermVar_wf, 
itermAdd_wf, 
itermConstant_wf, 
int_formula_prop_and_lemma, 
int_formula_prop_not_lemma, 
int_formula_prop_eq_lemma, 
int_term_value_var_lemma, 
int_term_value_add_lemma, 
int_term_value_constant_lemma, 
int_formula_prop_wf, 
false_wf, 
iff_weakening_equal
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
thin, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
intEquality, 
because_Cache, 
productEquality, 
independent_functionElimination, 
baseClosed, 
voidEquality, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
equalityTransitivity, 
equalitySymmetry, 
lambdaFormation, 
rename, 
addEquality, 
natural_numberEquality, 
axiomEquality, 
applyEquality, 
imageElimination, 
independent_isectElimination, 
unionElimination, 
pointwiseFunctionality, 
promote_hyp, 
baseApply, 
closedConclusion, 
productElimination, 
dependent_pairFormation, 
int_eqEquality, 
independent_pairFormation, 
computeAll, 
imageMemberEquality, 
universeEquality
Latex:
\mforall{}[T1,T2:Type].  \mforall{}[as:T1  List].  \mforall{}[bs:T2  List].    ||zip(as;bs)||  =  ||as||  supposing  ||as||  =  ||bs||
Date html generated:
2017_04_17-AM-08_55_08
Last ObjectModification:
2017_02_27-PM-05_10_44
Theory : list_1
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