Nuprl Lemma : tl_wf
∀[A:Type]. ∀[l:A List].  (tl(l) ∈ A List)
Proof
Definitions occuring in Statement : 
tl: tl(l)
, 
list: T List
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
universe: Type
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
, 
or: P ∨ Q
, 
cons: [a / b]
, 
top: Top
Lemmas referenced : 
list-cases, 
reduce_tl_nil_lemma, 
nil_wf, 
product_subtype_list, 
reduce_tl_cons_lemma, 
istype-void, 
list_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
Error :isect_memberFormation_alt, 
introduction, 
cut, 
hypothesisEquality, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesis, 
dependent_functionElimination, 
unionElimination, 
sqequalRule, 
promote_hyp, 
hypothesis_subsumption, 
productElimination, 
Error :isect_memberEquality_alt, 
voidElimination, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
Error :universeIsType, 
because_Cache, 
universeEquality
Latex:
\mforall{}[A:Type].  \mforall{}[l:A  List].    (tl(l)  \mmember{}  A  List)
Date html generated:
2019_06_20-PM-00_38_39
Last ObjectModification:
2018_10_08-PM-04_45_43
Theory : list_0
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