Is it permissible to remarry a wife divorced with a single, irreversible divorce (Talaq Ba'in) through a new contract without a guardian (wali)?

Irrevocable divorce (al-talaq al-ba'in) is when the husband cannot take his wife back without a new marriage contract. It is of two types: a major irrevocable divorce (baynunah kubra), which occurs after three divorces, and in which case she does not become lawful for him again unless she marries another man and that man divorces her. The second type is a minor irrevocable divorce (baynunah sughra), in which case reconciliation is possible with a new marriage contract that fulfills all conditions and pillars, including the presence of the wife's guardian, two just witnesses, and the صيغة (formula) of the contract. A divorce enacted by a marriage officiant (ma'dhun) does not make it irrevocable unless there is a reason for it to be so.