64 citations · 346 across the 53 of their papers we have counts for
13 papers · 1 filter
Algebraicity of the Brascamp-Lieb constants
Calin Chindris, Harm Derksen
We show that the Brascamp-Lieb (BL) constant BL(-,p) is a semi-algebraic function on the set of feasible data. Consequently, it is algebraic in the sense that it satisfies a polyno…
Polystability in positive characteristic and degree lower bounds for invariant rings
Harm Derksen, Visu Makam
We develop a representation theoretic technique for detecting closed orbits that is applicable in all characteristics. Our technique is based on Kempf's theory of optimal subgroups…
Maximum likelihood estimation for matrix normal models via quiver representations
Harm Derksen, Visu Makam
In this paper, we study the log-likelihood function and Maximum Likelihood Estimate (MLE) for the matrix normal model for both real and complex models. We describe the exact number…
Algebraic Methods for Tensor Data
Neriman Tokcan, Jonathan Gryak, Kayvan Najarian +1
We develop algebraic methods for computations with tensor data. We give 3 applications: extracting features that are invariant under the orthogonal symmetries in each of the modes,…
Invariant theory and wheeled PROPs
Harm Derksen, Visu Makam
We study the category of wheeled PROPs using tools from Invariant Theory. A typical example of a wheeled PROP is the mixed tensor algebra , whe…
The capacity of quiver representations and Brascamp-Lieb constants
Calin Chindris, Harm Derksen
Let be a bipartite quiver, a real representation of , and an integral weight of orthogonal to the dimension vector of . Guided by quiver invariant theoretic c…
An exponential lower bound for the degrees of invariants of cubic forms and tensor actions
Harm Derksen, Visu Makam
Using the Grosshans Principle, we develop a method for proving lower bounds for the maximal degree of a system of generators of an invariant ring. This method also gives lower boun…
Weyl's polarization theorem in positive characteristic
Harm Derksen, Visu Makam
Let be an -dimensional algebraic representation over an algebraically closed field of a group . For , we study the invariant rings for the diagon…
Generating invariant rings of quivers in arbitrary characteristic
Harm Derksen, Visu Makam
It is well known that the ring of polynomial invariants of a reductive group is finitely generated. However, it is difficult to give strong upper bounds on the degrees of the gener…
Degree bounds for semi-invariant rings of quivers
Harm Derksen, Visu Makam
We use recent results on matrix semi-invariants to give degree bounds on generators for the ring of semi-invariants for quivers with no oriented cycles.
Polynomial degree bounds for matrix semi-invariants
Harm Derksen, Visu Makam
We study the left-right action of on -tuples of matrices with entries in an infinite field . We show that invari…
Counterexamples to Okounkov's Log-Concavity Conjecture
Calin Chindris, Harm Derksen, Jerzy Weyman
We give counterexamples to Okounkov's log-concavity conjecture for Littlewood-Richardson coefficients.
The Combinatorics of Quiver Representations
Harm Derksen, Jerzy Weyman
We give a description of faces of all codimensions for the cones of weights of rings of semi-invariants of quivers. For a triple flag quiver and faces of codimension 1 this reduces…