Generators of Roos' example: -x -y -z -u -v;
Weights:                      1  1  1  1  1;
<*Limiting weight: 10;*>
Relations:
[x,x];
[x,y];
[x,z];
[y,z]-[x,u];
[z,z]+2 [x,v];
[y,u]-[v,x];
[z,u]-[y,v];
[z,v];
[u,v];
[v,v];