A note on characteristics of ordered sets

A Note on Naturally Ordered Sets in Semi-metric Spaces

Tripled partially ordered sets

In this paper, we introduce tripled partially ordered sets and monotone functions on tripled partiallyordered sets. Some basic properties on these new dened sets are studied and some examples forclarifying are given.

A Problem on Ordered Sets

1. Let S be an ordered set, of power 1 SI and order type 8 = 4, We denote by #* the converse of 4, i.e. the order type obtained from + by replacing every order relation x < y by the corresponding relation y < x, and by wrc the least ordinal number of power N,. It is easy to see that, if ISl=tQ, then S contains a subset S’ such that either s’ = w,, or 8’ = w**. For cardinals N, > w’. the corresp...

A Note on P-sets

A P-set is a set S of positive integers such that no element of S divides the sum of any two (not necessarily being different) larger elements. Erdös and Sárközy [2] conjectured that there exists a constant c > 0 such that for every P-set S we have |{s ∈ S : s ≤ N}| < N1−c for infinitely many integers N . For P-sets S consisting of pairwise coprime integers this conjecture has been proved by T....

A Note on Discrete Sets

We give several partial positive answers to a question of Juhász and Szentmiklóssy regarding the minimum number of discrete sets required to cover a compact space. We study the relationship between the size of discrete sets, free sequences and their closures with the cardinality of a Hausdorff space, improving known results in the literature.