Partitioning algorithms for the Euclidean matching and for the semi-matchin
g problem in the plane are introduced and analysed. The algorithms are anal
ogues of Karp's well-known dissection algorithm for the travelling salesman
problem. The algorithms are proved to run in time n log n and to approxima
te the optimal matching in the probabilistic sense. The analysis is based o
n the techniques developed in Karp (1977) and on the limit theorem of Redmo
nd and Yukich (1993) for quasiadditive functionals.