Combinatorics coding is a new data coding method based on combinatorics. Ordinal computing is the core technology of in the combinatorics coding. Ordinal properties of combinatorics coding is studied in this paper. Firstly, the combinatorics coding theory and the correlative basic concepts are described. Then, the properties of the ordinal are revealed. The study indicates that the value of ord...

I am a combinatorialist with diverse interests. The power of combinatorics derives from the wide applicability of its methods. Discrete structures arise throughout mathematics and science, yet all too often combinatorics is unnecessarily done in isolation. I aim to bridge the gap between combinatorics and other fields through collaborations with mathematicians and scientists from varied discipl...

To get some intuition, we begin with the group of real numbers R under addition. A trivial upper bound for the size of a sum set is |A + A| ≤ |A| 2+|A| 2 (equality is obtained when every pair of elements of A have a distinct sum). If we build A by taking elements of R at random, then we expect |A+A| to be very close to this upper bound, since the probability of a1+a2 = a3+a4 is very small (wher...

The signature coding for M active users out of T total users over a multiple access OR channel is considered. The mathematical problem is equivalent to the M -coverfree problem of extremal set theory. We survey the upper and lower bounds on the minimal code word length n(T,M), and present some code constructions. According to the current state of the theory, for 1 M T 1 2 M2 logM log T ≤ n(T,M)...

The profile of a hypergraph on n vertices is (f0 ..... fn) where fi denotes the number of /-element edges. The extreme points of the set of the profiles are determined for Sperner hyper-graphs satisfying some additional conditions. The results contain some old theorems of extremal set theory as particular cases.

Additive combinatorics (or perhaps more accurately, arithmetic combinatorics) is a branch of mathematics which lies at the intersection of combinatorics, number theory, Fourier analysis and ergodic theory. It studies approximate notions of various algebraic structures, such as vector spaces or fields. In recent years, several connections between additive combinatorics and theoretical computer s...

This tutorial is intended to give an accessible introduction to Hopf algebras. The mathematical context is that of representation theory, and we also illustrate the structures with examples taken from combinatorics and quantum physics, showing that in this latter case the axioms of Hopf algebra arise naturally. The text contains many exercises, some taken from physics, aimed at expanding and ex...

It is shown that every cyclic split system S defined on an n-set with #S > 2kn− (2k+1 2 ) for some k ≤ n−1 2 always contains a subset of k+1 pairwise incompatible splits provided one has min(k, n−(2k+1)) ≤ 3. In addition, some related old and new conjectures are also discussed.

A typical problem in extremal combinatorics is the following. Given a large number n and a set L, find the maximum cardinality of a family of subsets of a ground set of n elements such that the intersection of any two subsets has cardinality in L. We investigate the generalization of this problem, where intersections of more than 2 subsets are considered. In particular, we prove that when k − 1...

The concern of this paper is a famous combinatorial formula known under the name “exponential formula”. It occurs quite naturally in many contexts (physics, mathematics, computer science). Roughly speaking, it expresses that the exponential generating function of a whole structure is equal to the exponential of those of connected substructures. Keeping this descriptive statement as a guideline,...