Malachi ben Jacob ha-Kohen מלאכי בן יעקב הכהן

Yad Malachi (Livorno, 1767) has three parts: an alphabetical list of the Talmud's rules and terms with explanations, rules concerning the codifiers, and rules of decision. The book is still used when one needs to know what a phrase of the Gemara means or how Maimonides, the Tur and the Shulhan Arukh stand to one another.

He prepared his teacher's responsa for the press—Divrei Yosef of Joseph Ergas (Livorno, 1742). His own are Shivhei Todah (1744), a service commemorating Livorno's deliverance in the earthquake of 1742, the collection of poems and laments Shirei Zimrah, and responsa in manuscript.

The encyclopaedia names two teachers: Abraham Hayyim Raphael Rodrigues and the kabbalist Joseph Ergas, whom he succeeded as rabbi of Livorno after Ergas's death in 1730. That link is confirmed from both sides—in the article on him and in the article on Ergas. To call him Ergas's "principal student", however, has no warrant: only popular literature says so.

His dates cannot be established, and the disagreement is not a small one. The Encyclopaedia Judaica opens with "d. 1785–1790" and adds that "little is known of his life"; it gives no year of birth at all, and by its account he died in Tripoli, where he was apparently an emissary of the Land of Israel. The Livorno tradition says otherwise: born at Livorno between 1695 and 1700, died there in 1771 or 1772, and his grave is shown in Livorno. The gap reaches twenty years and the place of death is flatly opposed. The available sources cannot decide it, so both years are left empty and on the timeline he stands by the span of his work.