reserve L for Ortholattice,
  a, b, c for Element of L;

theorem Th10:
  the carrier of Benzene c= bool 3
proof
  let a be object;
A1: 0 c= 3 & Segm 1 c= Segm 3 by NAT_1:39;
  assume
A2: a in the carrier of Benzene;
A3: Segm 2 c= Segm 3 & 3 c= 3 by NAT_1:39;
  a = 0 or a = 1 or a = 3 \ 1 or a = 2 or a = 3 \ 2 or a = 3 by A2,Th9,
ENUMSET1:def 4;
  hence thesis by A1,A3;
end;
