Digital Steiner sets and Matheron semi-groups

Spanning sets and scattering sets in Steiner triple systems

A spanning set in a Steiner triple system is a set of elements for which each element not in the spanning set appears in at least one triple with a pair of elements from the spanning set. A scattering set is a set of elements that is independent, and for which each element not in the scattering set is in at most one triple with a pair of elements from the scattering set. For each v = 1,3 (mod 6...

Semi-θ-Open Sets and New Classes of Maps

Realization of a Certain Class of Semi-Groups as Value Semi-Groups of Valuations

Semi-planar Steiner quasigroups of cardinality 3n

It is well known that for each n ≡ 1 or 3 (mod 6) there is a planar Steiner quasigroup (briefly, squag) of cardinality n (Doyen (1969) and Quackenbush (1976)). A simple squag is semi-planar if every triangle either generates the whole squag or the 9-element subsquag (Quackenbush (1976)). In fact, Quakenbush has stated that there should be such semi-planar squags. In this paper, we construct a s...

Full Minimal Steiner Trees on Lattice Sets

Given a finite set of points P in the Euclidean plane, the Steiner problem asks us to constuct a shortest possible network interconnecting P. Such a network is known as a minimal Steiner tree. The Steiner problem is an intrinsically difficult one, having been shown to be NP-hard [7]; however, it often proves far more tractable if we restrict our attention to points in special geometric configur...