The stopped clause of the rounds on the nonmonomial part #
The modified second step of [Wlo09, Theorem 7.4.1] at m = 1 runs, along a shrinking chain of
opens, rounds of order reduction on the nonmonomial part N(𝓘) at the bound d, d descending
from max ord N(𝓘) to 2 (stepAChainState), then the monomial phase. The stopped clause of
ClauseTools.lean (the field stopped_never_blownUp of BMOmodFam) asks that a point at which
the stop predicate holds and which lies on no member of the boundary is never blown up later. The
centres of the rounds are of order ≥ d ≥ 2 for the transforms of (N(𝓘), d)
(roundValue_isOfOrderGe_nonmonomial); at a predicate point off the boundary the marked transform
of (𝓘, 1) has order ≤ 1 (ord_le_one_of_isSmoothTransversalIdealAt) and equals its own
nonmonomial part (the stalk of the monomial part is the unit ideal off the boundary), which the
transform identity hid ([Kol07, 111, Step 1]) makes the transform of (N(𝓘), d); so the centre
misses the point. Stage by stage the points over such a point keep the predicate
(IsSmoothTransversalIdealAt.stageMapAdd_of_forall_notMem_center) and stay off the boundary
(notMem_totalTransformSeqFrom_of_forall_notMem_center), hence miss every centre.
FiniteSuccession.StoppedClause.of_forall_notMem_center_of_isSmoothTransversalIdealAt: the generic shape: if no centre contains a predicate point off the boundary of its stage, the stopped clause holds, by a strong induction on the number of steps.notMem_center_of_isSmoothTransversalIdealAt_of_nonmonomial: the fact about one round: a list of order≥ d ≥ 2for(N(𝓘), d),dboundingord N(𝓘), has no centre through a predicate point off the boundary (ord_le_one_of_isSmoothTransversalIdealAt,stalkIdeal_nonmonomialPart,componentFactor_stalkIdeal_top_of_notMem,hid,ordAlongIdeal_le_ord_of_mem_support).BState.roundValue_stoppedClause,descentStateAux_stoppedClause,stepAFamOn_stoppedClause,stepAFunctor_stoppedClauseFam: one round, the descent (stoppedClause_shrinkAppend), the value on an open (stoppedClause_pullback,stoppedClause_eraseEmpty), the functor (stepAFunctor_fam_seqOn).stepACFunctor_stoppedClauseFam: the stopped clause of the composite of the rounds and the monomial phase (composeInduced_stoppedClauseFamwithstep2bFunctor_stoppedClauseFam).
Sources: the modified second step of [Wlo09, Theorem 7.4.1]; [Kol07, Definition 66 (4′)] for the
order of a centre and the transform identity of [Kol07, 111, Step 1]; the persistence lemmas of
StopPersistence.lean. The statements themselves are not in the sources.
Centres missing every predicate point off the boundary give the stopped clause: if no centre
of S contains a point of its stage at which the stop predicate holds and which lies on no member
of the boundary there, the clause holds. The points over such a point keep the predicate
(IsSmoothTransversalIdealAt.stageMapAdd_of_forall_notMem_center) and stay off the boundary
(notMem_totalTransformSeqFrom_of_forall_notMem_center), stage by stage (a strong induction on the
number of steps), hence miss the centres.
The fact about one round ([Kol07, Definition 66 (4′)] at d ≥ 2 against the order bound
ord_le_one_of_isSmoothTransversalIdealAt): along a list of order ≥ d for (N(𝓘), d) with d
bounding ord N(𝓘) and the transform identity hid, a point of a stage at which the stop predicate
holds for the marked transform of (𝓘, 1) and which lies on no member of the boundary is in no
centre. The centre carries ord_C N_i ≥ d ≥ 2; the nonmonomial part equals the ideal off the
boundary (the stalk of the monomial part is the unit ideal there); and the order of the mark-1
transform at a predicate point is at most 1.
The stopped clause of one round at the bound d ≥ 2 (mark 1), for the restricted induced
triple: StoppedClause.of_forall_notMem_center_of_isSmoothTransversalIdealAt with the order clause
roundValue_isOfOrderGe and notMem_center_of_isSmoothTransversalIdealAt_of_nonmonomial at
roundValue_isOfOrderGe_nonmonomial and nonmonomialOrdLe_restrict.
The stopped clause along the descent (threshold t ≥ 2): the initial state is the empty
list, and each link appends a round at a bound d ≥ t ≥ 2 (stoppedClause_shrinkAppend with
BState.roundValue_stoppedClause).
The stopped clause of the value of the rounds on U (the modified second step of
[Wlo09, Theorem 7.4.1], t = 2): the final state of the descent (descentStateAux_stoppedClause
at the canonical chain), restricted to U (stoppedClause_pullback) and cleaned of its empty
blow-ups (stoppedClause_eraseEmpty).
The stopped clause of the functor of the rounds (stepAFunctor at m = 1, t = 2;
stepAFunctor_fam_seqOn).
The stopped clause of the composite of the rounds and the monomial phase (stepACFunctor):
composeInduced_stoppedClauseFam from stepAFunctor_stoppedClauseFam and
step2bFunctor_stoppedClauseFam, with step2bFam_isOfOrderGe.