theorem Th25:
  i<=len G & j<=width G implies cell(G,i,j) is connected
proof
  assume
A1: i<=len G & j<=width G;
  then Int cell(G,i,j) is convex by GOBOARD9:17;
  then Cl Int cell(G,i,j) is connected by CONNSP_1:19;
  hence thesis by A1,GOBRD11:35;
end;
