SRG from polarity of Higman's symmetric design

G. Higman (1969) constructed a symmetric $2\textrm{-}(176,50,14)$ design with doubly transitive automorphism group $HS$ (see here for its incidence graph). Brouwer (1982) showed that this design admits a polarity with 176 absolute points, yielding an $\mathrm{SRG}(176,49,12,14)$ with automorphism group $S_8$ acting intransitively with orbits of length 8 and 168.

Number of vertices:$176$
Diameter:$2$
Intersection array:$\{49,36;1,14\}$
Spectrum:$49^1 5^{98} (-7)^{77}$
Automorphism group:$S_8$
Distance-transitive:No
Primitive




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Last updated: 21 July 2026