I want to lay out another example where I seem to be unable to use LKB+LUI as usual, for interactive unification (and suspect the problem has something to do with append-list).
I can email the grammar in question by request, if someone would like to debug this (alternatively, the grammar can be obtained by running valchg-lkt regression test from the branch no-lex-threading in the Matrix repo, commit 743298b ).
Here’s the gold tree for item 19 in the test:
The LUI chart in the current grammar (which yields no parse) shows that the VP edge is missing:
As has been usual lately, interactive unification produces a result:
The same. interactive unification without LUI gives me a failure (although after the first result, I no longer can shrink structures):