1 ) In a semantic-network data-processing system, a method executed by a data processor for enforcing consistent levels of abstractions for sibling nodes within a semantic network, whereby the average abstractness for each set of sibling nodes is calculated, and abstractness deviations from said average abstractness for each individual sibling node are summed, and alternative inheritance tree representations are proposed, and the alternative tree representation is chosen which has the smallest total sum of abstractness deviation.