X. Nguyen, M. I. Jordan and B. Sinopoli. A kernel-based learning approach to ad hoc sensor network localization. ACM Transactions on Sensor Networks, Vol. 1, pages 134--152, 2005.

In the analysis in Section 3.3, the following additional assumption is required: If a sensor's location is correctly classified with respect to all covering discs, then it is also correctly classified with respect to all non-covering discs.

This assumption is reasonable because for non-covering discs the sensor's location is farther away from the boundary, and so is usually easier to classify compared to covering discs.

Thanks to Duc Tran for helping point this out.