When it became clear in the early 1980s, however, that syntactic trees could be mapped to semantic representations by using compositional semantic rules associated with phrase structure rules in one-to-one fashion, this approach became broadly favored over pure proceduralist ones. In our earlier discussion in section 3.1) of meaning representations within logicist frameworks, we already foreshadowed the essentials of logical form computation. There we saw sample interpretive rules for a small number of phrase structure rules and vocabulary. The semantic rules, such as NP′ = Det′(N′), clearly indicate how logical forms of lower-level constituents should be combined to yield those of higher-level constituents. In the following figure, the sentence  “Thetis loves a mortal” has been interpreted by applying the earlier set of lexical and interpretive rules to the nodes of the phrase structure tree in a bottom-up, left-to-right sweep: 