math.RA — Rings and Algebras
Explicit non-inducible rooted cluster morphisms
The augmentation of the Markov cluster algebra is explicit but not inducible as a rooted cluster morphism. This answers a question of Chang and Zhu negatively.
math.RA — Rings and Algebras
The augmentation of the Markov cluster algebra is explicit but not inducible as a rooted cluster morphism. This answers a question of Chang and Zhu negatively.
math.AC — Commutative Algebra
We deduce from Bhatt's graded Cohen--Macaulay and vanishing results that an integer-graded absolute integral closure of a weighted polynomial ring over , modulo , is free with basis degrees smaller than the sum of the weights. A direct -adic expansion turns this degree bound into a uniform solution of the cusp relation modulo nilpotents. Consequently every ring admits a faithfully flat algebra with seminormal reduction, and every invertible -module becomes free after a faithfully flat extension of , answering a question of Drinfeld.