Nuprl Lemma : play-item-reachable
∀g:SimpleGame. ∀n:ℕ. ∀s:win2strat(g;n). ∀moves:strat2play(g;n;s). ∀i:ℕ(2 * n) + 2.
  (moves[i] ∈ {p:Pos(g)| sg-reachable(g;InitialPos(g);p)} )
Proof
Definitions occuring in Statement : 
sg-reachable: sg-reachable(g;x;y)
, 
strat2play: strat2play(g;n;s)
, 
win2strat: win2strat(g;n)
, 
play-item: moves[i]
, 
sg-init: InitialPos(g)
, 
sg-pos: Pos(g)
, 
simple-game: SimpleGame
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
all: ∀x:A. B[x]
, 
member: t ∈ T
, 
set: {x:A| B[x]} 
, 
multiply: n * m
, 
add: n + m
, 
natural_number: $n
Definitions unfolded in proof : 
sq_type: SQType(T)
, 
less_than: a < b
, 
play-item: moves[i]
, 
cand: A c∧ B
, 
nat_plus: ℕ+
, 
guard: {T}
, 
so_apply: x[s]
, 
so_lambda: λ2x.t[x]
, 
true: True
, 
less_than': less_than'(a;b)
, 
top: Top
, 
subtract: n - m
, 
lelt: i ≤ j < k
, 
sq_stable: SqStable(P)
, 
prop: ℙ
, 
false: False
, 
implies: P 
⇒ Q
, 
rev_implies: P 
⇐ Q
, 
not: ¬A
, 
iff: P 
⇐⇒ Q
, 
or: P ∨ Q
, 
decidable: Dec(P)
, 
uimplies: b supposing a
, 
uiff: uiff(P;Q)
, 
le: A ≤ B
, 
int_seg: {i..j-}
, 
nat: ℕ
, 
exists: ∃x:A. B[x]
, 
sg-reachable: sg-reachable(g;x;y)
, 
squash: ↓T
, 
subtype_rel: A ⊆r B
, 
and: P ∧ Q
, 
uall: ∀[x:A]. B[x]
, 
member: t ∈ T
, 
all: ∀x:A. B[x]
Lemmas referenced : 
subtype_base_sq, 
nat_plus_properties, 
nat_properties, 
int_seg_properties, 
seq-truncate-item, 
seq-len-truncate, 
minus-zero, 
mul-commutes, 
mul-distributes, 
omega-shadow, 
mul-distributes-right, 
two-mul, 
one-mul, 
le_reflexive, 
add-subtract-cancel, 
simple-game_wf, 
win2strat_wf, 
strat2play_wf, 
int_seg_wf, 
sg-init_wf, 
sg-reachable_wf, 
nat_plus_subtype_nat, 
le_weakening2, 
sg-legal2_wf, 
nat_plus_wf, 
multiply_nat_wf, 
add_nat_wf, 
mul_bounds_1a, 
sg-legal1_wf, 
squash_wf, 
nat_wf, 
all_wf, 
le-add-cancel-alt, 
zero-mul, 
add-mul-special, 
not-lt-2, 
decidable__lt, 
minus-minus, 
multiply-is-int-iff, 
set_subtype_base, 
subtract_wf, 
lelt_wf, 
seq-item_wf, 
equal_wf, 
less_than_wf, 
le-add-cancel2, 
seq-len_wf, 
mul-associates, 
less-iff-le, 
le_wf, 
le-add-cancel, 
add-zero, 
add_functionality_wrt_le, 
add-commutes, 
add-swap, 
add-associates, 
minus-one-mul-top, 
zero-add, 
minus-one-mul, 
minus-add, 
condition-implies-le, 
sq_stable__le, 
not-le-2, 
false_wf, 
decidable__le, 
int_subtype_base, 
add-is-int-iff, 
sg-pos_wf, 
seq-truncate_wf, 
play-item_wf, 
strat2play_subtype, 
strat2play-invariant-1
Rules used in proof : 
cumulativity, 
instantiate, 
levelHypothesis, 
addLevel, 
promote_hyp, 
sqequalIntensionalEquality, 
functionEquality, 
equalitySymmetry, 
equalityTransitivity, 
productEquality, 
multiplyEquality, 
minusEquality, 
intEquality, 
voidEquality, 
isect_memberEquality, 
lambdaEquality, 
independent_functionElimination, 
voidElimination, 
independent_pairFormation, 
unionElimination, 
independent_isectElimination, 
closedConclusion, 
baseApply, 
natural_numberEquality, 
addEquality, 
dependent_pairFormation, 
dependent_set_memberEquality, 
imageElimination, 
baseClosed, 
imageMemberEquality, 
rename, 
setElimination, 
applyLambdaEquality, 
sqequalRule, 
hypothesis, 
applyEquality, 
productElimination, 
because_Cache, 
isectElimination, 
hypothesisEquality, 
thin, 
dependent_functionElimination, 
sqequalHypSubstitution, 
extract_by_obid, 
introduction, 
cut, 
lambdaFormation, 
sqequalReflexivity, 
computationStep, 
sqequalTransitivity, 
sqequalSubstitution
Latex:
\mforall{}g:SimpleGame.  \mforall{}n:\mBbbN{}.  \mforall{}s:win2strat(g;n).  \mforall{}moves:strat2play(g;n;s).  \mforall{}i:\mBbbN{}(2  *  n)  +  2.
    (moves[i]  \mmember{}  \{p:Pos(g)|  sg-reachable(g;InitialPos(g);p)\}  )
Date html generated:
2018_07_25-PM-01_33_53
Last ObjectModification:
2018_06_20-AM-10_51_25
Theory : co-recursion
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