Families close to disjoint ones
✍ Scribed by P. Komjáth
- Book ID
- 105413966
- Publisher
- Akadmiai Kiad
- Year
- 1984
- Tongue
- English
- Weight
- 553 KB
- Volume
- 43
- Category
- Article
- ISSN
- 1588-2632
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📜 SIMILAR VOLUMES
We show that every drawing of C m \_C n with either the m n-cycles pairwise disjoint or the n m-cycles pairwise disjoint has at least (m&2) n crossings, for every m, n satisfying n m 3. This supports the long standing conjecture by Harary et al. that the crossing number of C m \_C n is (m&2) n.
A union closed family A is a finite family of sets such that the union of any two sets in A is also in A. The conjecture under consideration is Conjecture 1: For every union closed family A, there exists some x contained in at least half the members of A. We study the structure of such families (as
A long-standing conjecture states that the crossing number of the Cartesian product of cycles C m \_C n is (m&2) n, for every m, n satisfying n m 3. A crossing is proper if it occurs between edges in different principal cycles. In this paper drawings of C m \_C n with the principal n-cycles pairwise