a) Pertaining to region sets: given two region sets, to have a region in each set such that the two regions overlap.
Pertaining to regions: given two regions, to have at least one dimension in common if and only if, for each dimension the regions have in common, their respective ranges in the common dimension overlap. If two regions do not have any dimensions in common, the regions do not overlap.
c) Pertaining to ranges: given two ranges
- (A = [a_{lower}, a_{upper} ) and B = [b_{lower} , b_{upper} )), to overlap if and only if either a_{lower} = b_{lower} or
- (a_{lower} < b_{upper} and b_{lower} < a_{upper} ).
NOTE—See 9.1 of IEEE Std 1516.1-2010.