Almost Intersecting Families
نویسندگان
چکیده
Let $n > k 1$ be integers, $[n] = \{1, \ldots, n\}$. $\mathcal F$ a family of $k$-subsets $[n]$. The is called intersecting if $F \cap F' \neq \varnothing$ for all $F, \in \mathcal F$. It almost it not but to every there at most one $F'\in satisfying \varnothing$. Gerbner et al. proved that \geq 2k + 2$ then $|\mathcal F| \leqslant {n - 1\choose 1}$ holds families. Our main result implies the considerably stronger and best possible bound 1} (2 o(1))k$, $k\ge 3$.
منابع مشابه
Almost Intersecting Families of Sets
Let us write DF (G) = {F ∈ F : F ∩ G = ∅} for a set G and a family F . Then a family F of sets is said to be (≤ l)-almost intersecting (l-almost intersecting) if for any F ∈ F we have |DF (F )| ≤ l (|DF (F )| = l). In this paper we investigate the problem of finding the maximum size of an (≤ l)almost intersecting (l-almost intersecting) family F . AMS Subject Classification: 05D05
متن کاملAlmost Cross-Intersecting and Almost Cross-Sperner Pairs of Families of Sets
For a set G and a family of sets F let DF (G) = {F ∈ F : F ∩ G = ∅} and SF (G) = {F ∈ F : F ⊆ G or G ⊆ F}. We say that a family is l-almost intersecting, (≤ l)-almost intersecting, l-almost Sperner, (≤ l)-almost Sperner if |DF (F )| = l, |DF (F )| ≤ l, |SF (F )| = l, |SF (F )| ≤ l (respectively) for all F ∈ F . We consider the problem of finding the largest possible family for each of the above...
متن کاملChain Intersecting Families
Let F be a family of subsets of an n-element set. F is called (p,q)-chain intersecting if it does not contain chains A1 ( A2 ( · · · ( Ap and B1 ( B2 ( · · · ( Bq with Ap∩Bq = ∅. The maximum size of these families is determined in this paper. Similarly to the p = q = 1 special case (intersecting families) this depends on the notion of r-complementing-chain-pair-free families, where r = p + q − ...
متن کاملRegular Intersecting Families
We call a family of sets intersecting, if any two sets in the family intersect. In this paper we investigate intersecting families F of k-element subsets of [n] := {1, . . . , n}, such that every element of [n] lies in the same (or approximately the same) number of members of F . In particular, we show that we can guarantee |F| = o( ( n−1 k−1 ) ) if and only if k = o(n).
متن کاملG-Intersecting Families
Let G be a graph on vertex set [n], and for X [n] let N(X) be the union of X and it's neighborhood in G. A family of sets F 2 is G-intersecting if N(X) \ Y 6= ; for all X;Y 2 F . In this paper we study the cardinality and structure of the largest k-uniform G-intersecting families on a xed graph G.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Electronic Journal of Combinatorics
سال: 2021
ISSN: ['1077-8926', '1097-1440']
DOI: https://doi.org/10.37236/9609