Section 18.2.2.4 Translate Property Path Patterns contains a table that defines the translation of property path patterns into the algebraic syntax. I assume that the translation rules in this table are meant to be applied recursively, but the section doesn't say anything about that. In this sense, the definition of this translation step is incomplete.

To describe the issue in more detail, consider the following row of the table.

+----------------+-----------------+
| Algebra (path) | Translation     |
+----------------+-----------------+
...
| X seq(P, Q) Y  | X P ?V . ?V Q Y |
...

The P and the Q in this case may be arbitrary property path expressions. Therefore, the translation needs to be applied again to each of the two resulting property path patterns in the "Translation" column of this table (i.e., to X P ?V and to ?V Q Y).