Secant Varieties Working Group

meetings take place on:
Tuesday 10:00-11:30, room 403

in the summer semester 2019/2020:

1. 15.10.2019,

in the winter semester 2018/2019:

1. 9.01.2019,
2. 16.01.2019,
3. 23.01.2019,
4. 30.01.2019,
5. 6.02.2019,
6. 13.02.2019,
7. 20.02.2019,
8. 27.02.2019,
9. 6.03.2019,
10. 13.03.2019,
11. 20.03.2019 (in the room 408)
12. 27.03.2019
13. 10.04.2019 (in the room 321)
14. 16.07.2019

Research problems we try to address:

1. Find equations of secant varieties that do not vanish on cactus varieties.
2. For a fixed tensor find criteria for  to have border rank equal to .
3. High rank loci. For let be the closure of tensors in which have rank equal to . Is there an equality between  and   for ,  where denotes the join of  and ? (answer is no - recently solved by E. Ballico, A. Bernardi, E. Ventura 
4. For   , where  is generic from  we want to find decomposition  for . We would like to find an algorithm wich computes such a decomposition.
5. For where  are simple tensors with norm  and  is a random error with norm . Assuming  we want to find the funcition  such that   is the best rank 2 approximation and the norms  are bounded from above by some constant.

We are open to discuss any issues related to secant varieties, cactus varieties, tensor rank, Waring rank, and their border/cactus analogues, identifiability, apolarity, Hilbert schemes of points etc.