This question has become moot, as I have just removed the tags (in accordance with the current 3:0 vote). I will accept an answer ASAP, which seems to be tomorrow.
I noticed that the Edgeworth-box tag usually attracts basic homework questions. Since it is an elementary illustrative tool things are unlikely to be different in the future.
All on-topic questions should be covered by general-equilibrium or Pareto-optimality.
Should we remove this tag from the 13 tagged questions?