Nuprl Lemma : quicksort-int-null
∀[L:ℤ List]. uiff(↑null(quicksort-int(L));↑null(L))
Proof
Definitions occuring in Statement : 
quicksort-int: quicksort-int(L)
, 
null: null(as)
, 
list: T List
, 
assert: ↑b
, 
uiff: uiff(P;Q)
, 
uall: ∀[x:A]. B[x]
, 
int: ℤ
Definitions unfolded in proof : 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
uiff: uiff(P;Q)
, 
and: P ∧ Q
, 
uimplies: b supposing a
, 
rev_uimplies: rev_uimplies(P;Q)
, 
all: ∀x:A. B[x]
, 
subtype_rel: A ⊆r B
, 
prop: ℙ
, 
squash: ↓T
, 
true: True
, 
guard: {T}
, 
iff: P 
⇐⇒ Q
, 
implies: P 
⇒ Q
, 
top: Top
, 
so_lambda: λ2x.t[x]
, 
so_apply: x[s]
, 
rev_implies: P 
⇐ Q
Lemmas referenced : 
assert_of_null, 
quicksort-int_wf, 
list_wf, 
sorted-by_wf, 
le_wf, 
l_member_wf, 
permutation_wf, 
length_of_null_list, 
equal_wf, 
squash_wf, 
true_wf, 
quicksort-int-length, 
iff_weakening_equal, 
length_zero, 
assert_witness, 
null_wf3, 
subtype_rel_list, 
top_wf, 
assert_wf, 
subtype_rel_set, 
quicksort-int-nil
Rules used in proof : 
sqequalSubstitution, 
sqequalTransitivity, 
computationStep, 
sqequalReflexivity, 
isect_memberFormation, 
introduction, 
cut, 
independent_pairFormation, 
extract_by_obid, 
sqequalHypSubstitution, 
isectElimination, 
thin, 
intEquality, 
hypothesisEquality, 
hypothesis, 
productElimination, 
independent_isectElimination, 
dependent_functionElimination, 
applyEquality, 
lambdaEquality, 
setElimination, 
rename, 
setEquality, 
productEquality, 
sqequalRule, 
equalityTransitivity, 
equalitySymmetry, 
imageElimination, 
universeEquality, 
because_Cache, 
natural_numberEquality, 
imageMemberEquality, 
baseClosed, 
independent_functionElimination, 
isect_memberEquality, 
voidElimination, 
voidEquality, 
independent_pairEquality, 
lambdaFormation
Latex:
\mforall{}[L:\mBbbZ{}  List].  uiff(\muparrow{}null(quicksort-int(L));\muparrow{}null(L))
Date html generated:
2018_05_21-PM-07_35_14
Last ObjectModification:
2017_07_26-PM-05_09_29
Theory : general
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