MINIMAL DEFINING SETS OF
THE 2-(9,4,3) DESIGNS
D#1 | D#2 | D#3 | D#4 | D#5 | D#6 | D#7 | D#8 | D#9 | D#10 | D#11
See also George Havas, Julie L. Lawrence, Colin Ramsay, Anne Penfold Street and Emine Şule Yazıcı, Defining Set Spectra for Designs can have Arbitrarily Large Gaps, Preprint submitted to J. Combin. Designs.