A notorious open problem in the field of rendezvous search is to decide the rendezvous value of the symmetric rendezvous search problem on the line, when the initial distance apart between the two players is 2. We show that the symmetric rendezvous value is within the interval (4.1520, 4.2574), which considerably improves the previous best known result (3.9546, 4.3931). To achieve the improved bounds, we call upon results from absorbing markov chain theory and mathematical programming theory---particularly fractional quadratic programming and semidefinite programming. Moreover, we also establish some important properties of this problem, which may be of independent interest and useful for resolving this problem completely. Finally, we conjecture that the symmetric rendezvous value is asymptotically equal to 4.25 based on our numerical calculations.
Operations Research, May-June 2008; 56: 772 - 782