Explanation structures in XSEL
Karen Kukich · 1985
Relational Links The network fon,d by relational links is in some places more dense and in other places less dense than the network formed by generic links; arithmetic relationat links create more levels thus making the relational network denser, while abstract links tend to bridge long chains of facts, thus making the network sparser. To see this distinction, consider the arithmetic formula used by XSEL to calculate the total-disk-s,oace requirement: total.disk-space = ((total.application-disk.space + programmer.disk-space + total-data-file-disk-space) 125%) + sum of system-disk.space sum of I=age-and.swap-s13ace 233 The rules that execute this formula create at least five genedc links linking total-disk-space to total-application-disk-space, programmer-disk-space. total-data-lile-disk-space, one or more system-disk-spoce facts. and one or more page-and-swap-space facts. At the same time they create one relational link linking total-disk-space to three new intermediate level facts, total.user.