His statement, “Full siblings,” means a full brother or a full sister.

His statement, “by a son, a grandson, and a father,” means that a full sibling is excluded by any one of these three.

Thus, if someone dies leaving a son and a full brother, the full brother is excluded. If he dies leaving a grandson and a full brother, the full brother is excluded. If he dies leaving a full brother and a father, the full brother is excluded. If he dies leaving a full brother and a paternal grandfather, then—according to the preponderant view—the full brother is excluded, because the paternal grandfather is like the father.

His statement, “Paternal half-siblings by these,” refers to a brother through the father; “by these” means that he is excluded by a son, a grandson, and a father.

His statement, “and by a full sibling”: those who exclude a paternal half-brother are four: the son, the grandson, the father, and the full brother.

His statement, “Maternal half-siblings by a child, a descendant through a son, the father, and his father”: a maternal half-sibling means a brother through the mother or a sister through the mother. Such a sibling is excluded by four: a child, a descendant through a son, the father, and his father. This is the author’s detailed formulation, but we have previously stated that maternal half-siblings do not inherit in the presence of a male ascendant heir or a descendant heir.

His statement, “and the latter excludes every nephew and paternal uncle”: “the latter” means the father’s father, because the pronoun refers to the nearest antecedent.