High Quality Content by WIKIPEDIA articles! In mathematics, the Grothendieck group construction in abstract algebra constructs an abelian group from a commutative monoid in the most universal way. It takes its name from the more general construction in category theory, introduced by Alexander Grothendieck in his fundamental work of the mid-1950s that resulted in the development of K-theory, which led to his proof of the Grothendieck-Riemann-Roch theorem. The Grothendieck group is denoted by K or R.