2026/07/26 by Peyman Nasehpour
Mathematics · #math.AC #math.RA
In this paper, we investigate the subtractive closure operator in commutative hemiring theory. While this operator satisfies standard closure properties, it does not distribute over ideal addition, intersection, or multiplication in general. We introduce Kuratowski hemirings (where closure preserves joins) and nucleus hemirings (where closure preserves meets), providing explicit counterexamples and positive results for each. Key findings include: the standard semiring ℕ0 and the max-plus algebra are nucleus hemirings with multiplicative distributivity; the interval semiring T = [0,1] is Kuratowski and multiplicatively distributive but not nucleus; and polynomial hemirings S0[X,Y,Z] over zerosumfree hemirings form a broad class of non-nucleus counterexamples. We also correct a recent claim regarding distributivity over arbitrary intersections.