5 papers
Local cohomology modules with nonclosed support
Bhargav Bhatt, Linquan Ma
We construct noetherian rings admitting local cohomology modules with nonclosed support, or equivalently with infinitely many minimal primes; this answers a question of Huneke--Lyu…
Infinitely many associated primes of local cohomology modules of ramified regular local rings
Linquan Ma
We construct examples of local cohomology modules of ramified regular local rings with infinitely many associated primes and infinite Bass numbers.
Ulrich modules over local rings of dimension two
Srikanth B. Iyengar, Linquan Ma, Mark E. Walker
It is proved that Ulrich modules exist for a large class of local rings of dimension two. This complements earlier work of the authors and Ziquan Zhuang that described complete int…
Lim Cohen-Macaulay sequences of modules
Bhargav Bhatt, Mel Hochster, Linquan Ma
We introduce the notion of a lim Cohen-Macaulay sequence of modules. We prove the existence of such sequences in positive characteristic, and show that their existence in mixed cha…
Non-existence of Ulrich modules over Cohen-Macaulay local rings
Srikanth B. Iyengar, Linquan Ma, Mark E. Walker +1
Over a Cohen-Macaulay local ring, the minimal number of generators of a maximal Cohen-Macaulay module is bounded above by its multiplicity. In 1984 Ulrich asked whether there alway…