K connects certain verbs with particles like "in", "out", "up", and the like.
+-K-+
| |
The man came up
*The man arrived up
Particles that can be used in this way have K- disjoined
with everything else. (Most are also prepositions; a few, like
"away", are not.)
We distinguish between verbs that can take particles and those that do not, but among particle-taking verbs, we do not distinguish between specific verb-particle pairs: we allow "We sorted them out/*up", "We put them in/*over". Some verb-particle pairings are treated as idiomatic phrases: "It ended up unwanted"; in such cases, the verb-particle pairing is forced by the idiomatic construction.
Verbs that take particles may be transitive ("pick"), intransitive ("come"), or trans/intrans ("move"). With transitive verbs, the particle may either precede or follow the direct object: "We picked the dog up"; "We picked up the dog". This yields the following expression.
pick: (S- or ....) & ((K+ & O+) or ((O+ or B-) & {K+}));
^ particle ^ particle
precedes object follows object
The particle is almost always optional. (There are a few
exceptions, like "put", which requires either a particle or a
prepositional phrase: "We put it in", "*We put it".) However:
if we made the particle optional in both the "pre-object" case
and the "post-object case", then "We picked the dog" would
receive two parses. So it must be obligatory in one case,
optional in the other.
A further complication: with transitive verbs, the particle may always follow the object, but it may precede it only if the object is a full noun-phrase, not a pronoun: "We picked it up," "*We picked up it". We enforce this using post-processing. In the expression for transitive verbs, the O+ in the "particle-precedes-object" case is subscripted O*n+. Pronouns are then subscripted Ox-. Oxn links are then prohibited in post-processing.