claimroutineinferred_dep

Conditional expectations yield balanced labels

Claim·§4.4 Choosing the variable and factor groups·inside lemDeterministic balanced incidence labeling

Statement (paper)

One can fix the ava_v and the dfd_f for nonempty IfI_f one at a time, deterministically, so that the final value of ΦM(b+w)+ΞQn\frac{\Phi}{M(b+w)}+\frac{\Xi}{Qn} is at most two. Consequently cu⩽MD+2M(b+w)c_u\le\frac MD+\sqrt{2M(b+w)} for every u∈Bu\in\mathcal B and nt,g⩽nr+2Qnn_{t,g}\le\frac nr+\sqrt{2Qn} for all t∈[Q]t\in[Q], g∈[r]g\in[r], and under these give cu⩽2M/Dc_u\le 2M/D and nt,g⩽2n/rn_{t,g}\le 2n/r.

In plain English

The labels ava_v and dfd_f (nonempty IfI_f) can be fixed one at a time deterministically so that ΦM(b+w)+ΞQn⩽2\frac{\Phi}{M(b+w)}+\frac{\Xi}{Qn}\le 2. This gives cu⩽M/D+2M(b+w)c_u\le M/D+\sqrt{2M(b+w)} and nt,g⩽n/r+2Qnn_{t,g}\le n/r+\sqrt{2Qn}, which under the hypotheses become cu⩽2M/Dc_u\le 2M/D and nt,g⩽2n/rn_{t,g}\le 2n/r.

Why it's here

By the previous claim the random labeling has expected value of the combined potential at most 2, so the method of conditional expectations, choosing each label to not increase the conditional expectation, yields a fixed labeling with value at most 2. Since each potential is a sum of squared deviations, it bounds every single deviation by a square root, and the size hypotheses 2(b+w)D2⩽M2(b+w)D^2\le M and 2Qr2⩽n2Qr^2\le n make the square-root terms at most M/DM/D and n/rn/r, giving the two stated balance bounds of the lemma.
Classified routine:
Standard method of conditional expectations (derandomization, Erdős–Selfridge / Raghavan–Spencer) applied to the expected potential bound from the previous claim, followed by a bound on each squared deviation and arithmetic using the size hypotheses.

Sources

PaperOpen
Section
§4.4 Choosing the variable and factor groups
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main_full_version.tex:2496
Leannot aligned

Phase 2 aligns this node to a Lean declaration.

Friction

  • info
    inferred_dep
    outline: "Conditional expectations yield balanced labels" rests on claim-lem-incidence-labels-1