The authors are very grateful to the referees for their many helpful suggestions and corrections, especially the observation that Gauss considered the associative law in 1801.
About the Authors
Rob Bradley is a professor in the department of mathematics and computer science at Adelphi University. With Ed Sandifer, he wrote Cauchy’s Cours d’analyse: An Annotated Translation and edited Leonhard Euler: Life, Work and Legacy. He is chairman of HOM SIGMAA (the History of Mathematics Special Interest Group of the MAA) and president of the Euler Society.
Salvatore J. Petrilli, Jr. is an assistant professor at Adelphi University. He has a B.S. in mathematics from Adelphi University and an M.A. in mathematics from Hofstra University. He received the Ed.D. in mathematics education from Teachers College, Columbia University, where his advisor was J. Philip Smith. His research interests include history of mathematics and mathematics education.