Dan earned his BA from Dartmouth College in 1976 and his PhD from the University of Wisconsin-Madison in 1980. He taught at the University of Texas from 1980 to 1983, and Amherst College from 1983 to 2017. He was the editor of the American Mathematical Monthly from 2007 to 2011.
Bicycle or Unicycle? (with Stan Wagon), MAA Press, 2020.
How To Prove It, Cambridge University Press, 1994. 2nd edition, 2006. 3rd
Philosophies of Mathematics (with Alexander George), Wiley-Blackwell, 2002.
Calculus: A Rigorous First Course, Dover Publications, 2016.
Which Way Did the Bicycle Go? (with Joseph Konhauser and Stan Wagon),
Mathematical Association of America, 1996.