In the paper “Formal Basis of a Language Universal” by Miloš Stanojević and Mark Steedman in Computational Linguistics 47:1 (https://doi.org/10.1162/coli_a_00394), there is an error in example (12) on page 17.
The two occurrences of the notation ∖W should appear as |W. The paper has been updated so that the paragraph reads:
In the full theory, these rules are generalized to “second level” cases, in which the secondary function is of the form (Y|Z)|W such as the following “forward crossing” instance, in which — matches either / or ∖ in both input and output:
The Forward Crossing Level Two Composition Rule
X/×Y (Y∖Z)|W ⇒B× (X∖Z)|W (B×2)