Classification of resolvable balanced incomplete block designs — the unitals on 28 points

Petteri Kaski, Patric Östergård
2009 Mathematica Slovaca  
AbstractApproaches for classifying resolvable balanced incomplete block designs (RBIBDs) are surveyed. The main approaches can roughly be divided into two types: those building up a design parallel class by parallel class and those proceeding point by point. With an algorithm of the latter type — and by refining ideas dating back to 1917 and the doctoral thesis by Pieter Mulder — it is shown that the list of seven known resolutions of 2-(28, 4, 1) designs is complete; these objects are also known as the resolutions of unitals on 28 points.
doi:10.2478/s12175-009-0113-8 fatcat:soxakboa5jemlb46mri2eqmtmi