Exploring the Frontiers of Feasible Computation. The project aims to delineate the boundary between feasible and infeasible computational problems. A problem is considered feasible if there is an algorithm to solve it in worst-case time bounded by a polynomial in the input size. This is probably impossible for the important class of NP-complete problems. However, typical examples of NP-complete problems can often be solved in polynomial time, because worst-case problems are rare. The project is ....Exploring the Frontiers of Feasible Computation. The project aims to delineate the boundary between feasible and infeasible computational problems. A problem is considered feasible if there is an algorithm to solve it in worst-case time bounded by a polynomial in the input size. This is probably impossible for the important class of NP-complete problems. However, typical examples of NP-complete problems can often be solved in polynomial time, because worst-case problems are rare. The project is relevant to public-key cryptography, where breaking an encryption scheme should be infeasible, and to many real-life situations where NP-complete problems need to be solved, either exactly or approximately.Read moreRead less
Multicast in Single-Hop and Multi-Hop WDM Optical Networks. The emerging Wavelength-Division-Multiplexing (WDM) optical network is a promising candidate for next-generation Internet, which provides enormous bandwidth and fast connectivity. Multicast in WDM networks is a fundamental problem which has wide applications including teleconferencing, entertainment distribution, etc. In this project we investigate the multicast and constraint multicast problems in both single-hop and multi-hop WDM netw ....Multicast in Single-Hop and Multi-Hop WDM Optical Networks. The emerging Wavelength-Division-Multiplexing (WDM) optical network is a promising candidate for next-generation Internet, which provides enormous bandwidth and fast connectivity. Multicast in WDM networks is a fundamental problem which has wide applications including teleconferencing, entertainment distribution, etc. In this project we investigate the multicast and constraint multicast problems in both single-hop and multi-hop WDM networks by studying their computational complexities and devising scalable, high-quality approximation algorithms for them. The developed algorithms significantly improve the network performance and scalability, and the innovative approaches and algorithm techniques developed in this project are also applicable to other routing problems.Read moreRead less
Expressive power and complexity of temporal logics for model-checking. Hardware verification based upon mathematical logic is now routinely
used in industry to verify the correctness of large digital circuits
using a technique called model-checking. Such discrete systems move
from one state to another according to the regular ticks of a clock.
The challenge now is to find tractable methods for reasoning about
real-time systems and hybrid systems that move in a continuous manner
with respec ....Expressive power and complexity of temporal logics for model-checking. Hardware verification based upon mathematical logic is now routinely
used in industry to verify the correctness of large digital circuits
using a technique called model-checking. Such discrete systems move
from one state to another according to the regular ticks of a clock.
The challenge now is to find tractable methods for reasoning about
real-time systems and hybrid systems that move in a continuous manner
with respect to time: examples include aeroplanes flying according to
the laws of physics and a moving robot arm. We shall invent new logics
which are specifically tailored for tractable reasoning about
real-time and hybrid systems.Read moreRead less