New Bounds on Map Labeling with Circular Labels

We present new approximation algorithms for the NP-hard problems of labeling points with maximum-size uniform circles and circle pairs (MLUC and MLUCP) Our algorithms build on the important concept of maximal feasible region and new algorithmic techniques We obtain several results: a (2.98 + e)-approximation for MLUC, improving previous factor 3.0 + e; a (1.491 + e)-approximation for MLUCP, improving previous factor 1.5; and the first non-trivial lower bound 1.0349 for both MLUC and MLUCP, improving previous lower bound 1+O(1/n).