Pith. sign in

REVIEW

Uniform intersecting families with large covering number

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 2106.05344 v3 pith:4HKFUVBG submitted 2021-06-09 math.CO cs.DM

classification math.COcs.DM
keywords coveringintersectingmathcalnumberchoosefamilylargelfloor
verification ladder T0 review T1 audit T2 compute T3 formal

Signed reviews

No signed human review yet.

0 comments
abstract

A family $\mathcal F$ has covering number $\tau$ if the size of the smallest set intersecting all sets from $\mathcal F$ is equal to $\tau$. Let $M(n,k,\tau)$ stand for the size of the largest intersecting family $\mathcal F$ of $k$-element subsets of $\{1,\ldots,n\}$ with covering number $\tau$. It is a classical result of Erd\H os and Lov\'asz that $M(n,k,k)\le k^k$ for any $n$. In this short note, we explore the behaviour of $M(n,k,\tau)$ for $n<k^2$ and large $\tau$. The results are quite surprising: For example, we show that $M(n,k,\tau) =(1-o(1)){n-1\choose k-1}$, if $n = \lfloor k^{3/2}\rfloor$, and $\tau\le k-k^{3/4+o(1)}$ as $k\to\infty$; $M(n,k,\tau) <e^{-ck^{1/2}}{n\choose k}$, if $n = \lfloor k^{3/2}\rfloor$ and $\tau>k-\frac 12k^{1/2}$.

Discussion (0). Continue with ORCID to comment.

Pith tools