[Theory Seminar] Guy Kortsarz

October 16, 2019 @ 12:00 pm – 1:00 pm

Speaker: Guy Kortsarz
Affiliation: Rutgers Universty – Camden

Title: A survey on the Directed Steiner tree problem
The directed Steiner problem is one of the most important problems in optimization, and in particular is more general than Group Steiner and other problems.

I will discuss the (by now classic) 1/\epsilon^3 n^epsilon approximation for the problem by Charikar et al (the algorithm was invented by Kortsarz and Peleg and is called recursive greedy. A technique who people in approximation should know). The running time is more than n^{1/epsilon}. One of the most important open questions in Approximation Algorithms is if there is a polynomial time polylog ratio for this problem. This is open from 1997.

I will discuss the Group Steiner problem ( a special case of the Directed Steiner problem) and the Directed Steiner Forest (a generalization of the Directed Steiner problem) and many more related problems.