A method includes receiving layout data representing a plurality of patterns. The layout data includes a plurality of layers and spaces identified between adjacent patterns. In at least one layer of the plurality of layers, the adjacent patterns violate a G0-rule. The method further includes determining whether each identified space is a critical G0-space. The identified space is determined to be a critical G0-space if a portion of at least one adjacent pattern that is removed merges two adjacent odd-loops of G0-spaces into a single even loop or G0 spaces or alternatively, if a portion of an adjacent pattern that is removed converts one odd-loop of G0-spaces to a non-loop of G0-spaces. The method further includes receiving a modification of at least one adjacent pattern and updating a spacing of a layer that is adjacent to the layers within the adjacent pattern that violate the G0-rule.