Discrete Mathematics and Combinatorics Commons^™

Cwatsets: Weights, Cardinalities, And Generalizations, Richard Mohr

Mathematical Sciences Technical Reports (MSTR)

This report provides an upper bound on the average weight of an element in a cwatset and discusses the ratio of the cardinality of a cwatset to the cardinality of the group containing the cwatset. The concept of a generalized cwatset is also introduced.

Combinatorics And Campus Security, Arthur T. Benjamin

All HMC Faculty Publications and Research

One day I received electronic mail from our director of campus security [Gilbraith 1993]:

"I have a puzzle for you that has practical applications for me. I need to know how many different combinations there are for our combination locks. A lock has 5 buttons. In setting the combination you can use only 1button or as many as 5. Buttons may be pressed simultaneously and / or successively, but the same button cannot be used more than once in the same combination.

I had a student (obviously not a math major) email me that there are only 120 possibilities, but …

A Survey Of Hadamard Difference Sets, James A. Davis, Jonathan Jedwab

Department of Math & Statistics Faculty Publications

A (v, k, λ) difference set is a k-element subset D of a group G of order v for which the multiset {d₁d₂^-1 : d1, d₂ ∈ D, d₁ ≠ d₂} contains each nonidentity element of G exactly λ times. A difference set is called abelian, nonabelian or cyclic according to the properties of the underlying group. Difference sets are important in design theory because they are equivalent to symmetric (v, k, λ) designs with a regular automorphism group [L].

Exponent Bounds For A Family Of Abelian Difference Sets, K. T. Arasu, James A. Davis, Jonathan Jedwab, Siu Lun Ma, Robert L. Mcfarland

Department of Math & Statistics Faculty Publications

Which groups G contain difference sets with the parameters (v, k, λ)= (q³ + 2q² , q² + q, q), where q is a power of a prime p? Constructions of K. Takeuchi, R.L. McFarland, and J.F. Dillon together yield difference sets with these parameters if G contains an elementary abelian group of order q² in its center. A result of R.J. Turyn implies that if G is abelian and p is self-conjugate modulo the exponent of G, then a necessary condition for existence is that the exponent …