Nuprl Lemma : append_cancel
∀[A:Type]. ∀[as,bs,cs:A List].  bs = cs ∈ (A List) supposing (as @ bs) = (as @ cs) ∈ (A List)
Proof
Definitions occuring in Statement : 
append: as @ bs
, 
list: T List
, 
uimplies: b supposing a
, 
uall: ∀[x:A]. B[x]
, 
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
, 
append: as @ bs
, 
all: ∀x:A. B[x]
, 
so_lambda: so_lambda(x,y,z.t[x; y; z])
, 
top: Top
, 
so_apply: x[s1;s2;s3]
, 
guard: {T}
, 
and: P ∧ Q
Lemmas referenced : 
list_induction, 
uall_wf, 
list_wf, 
isect_wf, 
equal_wf, 
append_wf, 
list_ind_nil_lemma, 
list_ind_cons_lemma, 
cons_wf, 
reduce_tl_cons_lemma, 
and_wf, 
tl_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
thin, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
hypothesisEquality, 
sqequalRule, 
lambdaEquality, 
cumulativity, 
hypothesis, 
because_Cache, 
independent_functionElimination, 
dependent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
axiomEquality, 
equalityTransitivity, 
equalitySymmetry, 
lambdaFormation, 
rename, 
universeEquality, 
dependent_set_memberEquality, 
independent_pairFormation, 
applyLambdaEquality, 
setElimination, 
productElimination, 
independent_isectElimination
Latex:
\mforall{}[A:Type].  \mforall{}[as,bs,cs:A  List].    bs  =  cs  supposing  (as  @  bs)  =  (as  @  cs)
Date html generated:
2017_04_17-AM-08_13_18
Last ObjectModification:
2017_02_27-PM-04_39_04
Theory : list_1
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