Theory Seminar
— 4:00pm
Location:
In Person and Virtual ET

Gates Hillman 8102 and Zoom
Speaker:
VERA TRAUB
,
Postdoctoral Researcher
https://people.math.ethz.ch/~vtraub/
BetterThan2 Approximations for Weighted Tree Augmentation
The Weighted Tree Augmentation Problem (WTAP) is one of the most basic connectivity augmentation problems. It asks how to increase the edgeconnectivity of a given graph from 1 to 2 in the cheapest possible way by adding some additional edges from a given set. There are many standard techniques that lead to a 2approximation for WTAP, but despite much progress on special cases, the factor 2 remained unbeaten for several decades.
In this talk we present two algorithms for WTAP that improve on the longstanding approximation ratio of 2. The first algorithm is a relative greedy algorithm, which starts with a simple, though weak, solution and iteratively replaces parts of this starting solution by stronger components. This algorithm achieves an approximation ratio of (1 + ln 2 + epsilon) < 1.7. Second, we present a local search algorithm that achieves an approximation ratio of 1.5 + epsilon (for any constant epsilon > 0).
This is joint work with Rico Zenklusen.
In Person and Zoom Participation. See announcement.
Event Website:
http://theory.cs.cmu.edu/
For More Information:
anupamg@cs.cmu.edu