Nuprl Lemma : firstn_append_front_singleton
∀[L:Top List]. ∀a:Top. (firstn(||L @ [a]|| - 1;L @ [a]) ~ L)
Proof
Definitions occuring in Statement : 
firstn: firstn(n;as)
, 
length: ||as||
, 
append: as @ bs
, 
cons: [a / b]
, 
nil: []
, 
list: T List
, 
uall: ∀[x:A]. B[x]
, 
top: Top
, 
all: ∀x:A. B[x]
, 
subtract: n - m
, 
natural_number: $n
, 
sqequal: s ~ t
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
Lemmas referenced : 
length-singleton, 
firstn_append_front, 
cons_wf, 
top_wf, 
nil_wf, 
list_wf
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
lambdaFormation, 
lemma_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
hypothesisEquality, 
hypothesis, 
dependent_functionElimination, 
sqequalRule, 
lambdaEquality, 
sqequalAxiom, 
because_Cache
Latex:
\mforall{}[L:Top  List].  \mforall{}a:Top.  (firstn(||L  @  [a]||  -  1;L  @  [a])  \msim{}  L)
Date html generated:
2016_05_14-PM-02_08_31
Last ObjectModification:
2015_12_26-PM-05_06_46
Theory : list_1
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