# Steiner System

In combinatorial mathematics, a Steiner system (named after Jakob Steiner) is a type of block design, specifically a t-design with λ = 1 and t ≥ 2.

A Steiner system with parameters t, k, n, written S(t,k,n), is an n-element set S together with a set of k-element subsets of S (called blocks) with the property that each t-element subset of S is contained in exactly one block. In an alternate notation for block designs, an S(t,k,n) would be a t-(n,k,1) design.

This definition is relatively modern, generalizing the classical definition of Steiner systems which in addition required that k = t + 1. An S(2,3,n) was (and still is) called a Steiner triple system, while an S(3,4,n) was called a Steiner quadruple system, and so on. With the generalization of the definition, this naming system is no longer strictly adhered to.

As of 2012, an outstanding problem in design theory is if any nontrivial Steiner systems have t ≥ 6. It is also unknown if infinitely many have t = 5.

### Other articles related to "steiner system":

Constructions of The Mathieu Groups - Automorphism Groups of Steiner Systems
... There exists up to equivalence a unique S(5,8,24) Steiner system W24 (the Witt design) ... M24 is the automorphism group of this Steiner system that is, the set of permutations which map every block to some other block ... Similarly, there exists up to equivalence a unique S(5,6,12) Steiner system W12, and the group M12 is its automorphism group ...
Fano Plane - Steiner System
... The Fano plane, as a block design, is a Steiner triple system ... As such, it can be given the structure of a quasigroup ...
Projective Linear Group - Finite Fields - Mathieu Groups
... One begins with the projective plane over the field with four elements, which is a Steiner system of type S(2,5,21) – meaning that it has 21 points, each ... One calls this Steiner system W21 ("W" for Witt), and then expands it to a larger Steiner system W24, expanding the symmetry group along the way to the projective general linear group ...

### Famous quotes containing the words system and/or steiner:

I am fearful that the paper system ... will ruin the state. Its demoralizing effects are already seen and spoken of everywhere ... I therefore protest against receiving any of that trash.
Andrew Jackson (1767–1845)

Language can only deal meaningfully with a special, restricted segment of reality. The rest, and it is presumably the much larger part, is silence.
—George Steiner (b. 1929)