How is the estate of a deceased wife, whose parents and child predeceased her, calculated when she leaves behind a husband, one son, and two full brothers?

If a woman dies leaving a husband, a son, and two full brothers, and no other heirs, then the husband receives one-fourth due to the presence of a lineal descendant. The remainder goes to the son by way of ta'sib (residuary heirship). The two full brothers receive nothing because they are completely excluded (by the son). The estate is divided into four shares: one share for the husband and three shares for the son. Everything the wife left behind, including money, gold, new clothes, and old clothes, is considered part of the estate to be divided among the heirs. If a child is born alive and then dies after its mother, it also inherits from her and shares with the other son in what remains after the husband's one-fourth. Then, its share is divided among its own heirs. If it leaves no one behind except its father and its brother, then its entire share goes to its father, and its brother receives nothing. It is permissible to visit her grave and supplicate for her at all times and on all days. She feels your visit, benefits from your supplication, and responds to your greetings.