Xiaomin Bao - A note on the blocking sets in S(3,6,22) and S(4,7,23)

We use the same notations and terminologies as in [1,2]. In [1] it is implied that there are two different types of blocking sets of size nine in S(3,6,22): N₁ and N₀. In [2] the author claims that up to isomorphism there are exactly three types of blocking sets of size eleven in S(4,7,23): E₀, E, E₁. In this short note we prove that N₁ and N₀ are actually the same type of blocking set in S(3,6,22); while E and E₁ are actually the same type of blocking set in S(4,7,23).

2.  to 3em, Blocking sets in the large Mathieu designs, II: the case S(4,7,23). J. Inform. Optim. Sci. (1988), 263-278.