Directed graphs and boron trees

作者：Sokic Miodrag^*

来源：Journal of Combinatorial Theory - Series A, 2015, 132: 142-171.

DOI：10.1016/j.jcta.2014.12.006

• Ramsey property
• Ordering property
• Expansion property
• Fraisse structures

Let L-1 and L-2 be two disjoint relational signatures. Let K-1 and K-2 be Ramsey classes of rigid relational structures in L-1 and L-2 respectively. Let K-1*K-2 be the class of structures in L-1 boolean OR L-2 whose reducts to L-1 and L-2 belong to K-1 and K-2 respectively. We give a condition on K-1 and K-2 which implies that K-1*K-2 is a Ramsey class. This is an extension of a result of M. Bodirsky.
In the second part of this paper we consider classes OS(2), OS(3), OB and OH which are obtained by expanding the class of finite dense local orders, the class of finite circular directed graphs, the class of finite boron tree structures, and the class of rooted trees respectively with linear orderings.

• 出版日期2015-5