"Source: Text/Incidence/IncidenceGeometry.text";
"Line: 185";
"Date: Fri Sep 26 12:10:10 2025";
"Main: Fri Sep 26 14:29:19 2025";
// original file: Text/Incidence/IncidenceGeometry.text, line: 185
// Example: H155E3 ()
print "Example: H155E3";
ei := GetEchoInput();
SetEchoInput(true);
HoffmanSingletonGraph := function()
  pentagram := Graph< 5 | { {1,3}, {3,5}, {5,2}, {2,4}, {4,1} } >;
  pentagon := PolygonGraph(5);
  PP := pentagram join pentagon;
  HS := &join [ PP : i in [1..5] ];
  return HS + { { Vertices(HS) | i + j*10, k*10 + 6 + (i+j*k) mod 5 } : 
                                 i in [1..5], j in [0..4], k in [0..4] };
end function;
ig := IncidenceGeometry(HoffmanSingletonGraph());
SetEchoInput(ei);
