11 papers
Open problems in deformations of Artinian algebras, Hilbert schemes and around
Joachim Jelisiejew
We review the open problems in the theory of deformations of zero-dimensional objects, such as algebras, modules or tensors. We list both the well-known ones and some new ones that…
Hankel and Multiplication Tensor Completions for Cactus Rank
Alessandra Bernardi, Joachim Jelisiejew, Oriol Reig Fité
We show that the Hankel flat extension formulation of the cactus algorithm is equivalent to a completion problem for multiplication tensors of Artinian Gorenstein algebras. The unk…
Unrestrictions and concise secant varieties
Jakub JagieÅÅa, Joachim Jelisiejew
We introduce the concise secant varieties, which are, informally speaking, modular partial desingularisations of secant varieties to Segre embeddings. More precisely, they are proj…
On a conjecture by Michael Wemyss regarding the calculation of GV invariants
Joachim Jelisiejew, Agata Smoktunowicz
Contraction algebras are noncommutative algebras introduced by Donovan and Wemyss to classify of 3-dimensional flops. Wemyss conjectures that contraction algebras can be deformed t…
The Hilbert scheme of points on a threefold: broken Gorenstein structures and linkage
Joachim Jelisiejew, Ritvik Ramkumar, Alessio Sammartano
We investigate the Hilbert scheme of points on a smooth threefold. We introduce a notion of broken Gorenstein structure for finite schemes, and show that its existence guarantees s…
Behrend's function is not constant on
J. Jelisiejew, M. Kool, R. F. Schmiermann
We prove the statement in the title for .