In this paper, using group actions, we introduce a new method for constructing partial geometric designs (sometimes referred to as 1 1 2 -designs). Using this new method, we construct several infinite families of partial geometric designs by investigating the actions of various linear groups of degree two on certain subsets of F 2 q . Moreover, by computing the stabilizers of such subsets in various linear groups of degree two, we are also able to construct a new infinite family of balanced incomplete block designs. (2010) 05B05 · 05E30 1 Introduction Combinatorial designs are an important subject of combinatorics intimately related to finite geometry [2], [11], [16], [21], with applications in statistics and experiment design [3], [14], coding and information theory [1], [12], [15], [17], and cryptography [9], [26], [30].
Mathematics Subject ClassificationRecent literature shows an increased interest in the study of partial geometric designs. Since their concurrence matrices have three eigenvalues (with one equal to zero), partial geometric designs provide a partial solution to Bailey's well-known question [6] concerning when the concurrence matrix of a connected binary equireplicant proper incomplete block design has exactly three eigenvalues. Olmez,in [27], introduced a method related to difference sets for constructing