M. Lothaire is the pseudonym of a group of mathematicians, many of whom were students of Marcel-Paul Schützenberger

Marcel-Paul Schützenberger

Marcel-Paul "Marco" Schützenberger was a French mathematician and Doctor of Medicine. His work had impact across the fields of formal language, combinatorics, and information theory...

. The name is used as the author of several of their joint books about combinatorics on words

Combinatorics on words

Combinatorics on words is a branch of mathematics which applies combinatorics to words and formal languages. The study of combinatorics on words arose independently within several branches of mathematics, e.g. number theory, group theory and probability...

. He is named for Lothair I

Lothair I

Lothair I or Lothar I was the Emperor of the Romans , co-ruling with his father until 840, and the King of Bavaria , Italy and Middle Francia...

.

Mathematicians in the group have included
Jean Berstel,
Veronique Bruyere,
Julien Cassaigne,
Christian Choffrut,
Robert Cori,
Jacques Desarmenien,
Volker Diekert,
Dominique Foata

Dominique Foata

Dominique Foata is a mathematician who works in enumerative combinatorics. With Pierre Cartier and Marcel-Paul Schützenberger he pioneered the modern approach to classical combinatorics, that lead, in part, to the current blossoming of algebraic combinatorics...

,
Christiane Frougny,
Guo-Niu Han,
Tero Harju,
Juhani Karhumäki,
Alain Lascoux,
Bernard Leclerc,
Aldo De Luca,
Filippo Mignosi,
Dominique Perrin,
Jean-Éric Pin,
Giuseppe Pirillo,
Wojciech Plandowski,
Antonio Restivo,
Christophe Reutenauer,
Jacques Sakarovitch,
Marcel-Paul Schützenberger,
Patrice Séébold,
Imre Simon

Imre Simon

Imre Simon was a Hungarian-born Brazilian mathematician and computer scientist. His research mainly focused on theoretical computer science, Automata theory, and tropical mathematics, a subject he founded, and which was so named because he lived in Brazil. He was a professor of mathematics at the...

,
Jean-Yves Thibon,
and Stefano Varricchio.