  Explicit results of the van der Pauw method for a sample containing an
isolated hole are presented together with experimental confirmation. Results of
measurements and numerical analysis strongly suggest that four probe
resistivities obey inequality similar in the form to the famous van der Pauw
equation. The inequality seems to be valid for any sample with an isolated hole
and contacts located on the same edge, however rigorous proof is not given. The
inequality can be used for experimental detection of the sample quality.
