Obstacles and regions
Sandiway Fong[*] and Christiane Fellbaum[**]
[*] NEC Research Institute, Princeton NJ, USA
[**] Princeton University, Princeton NJ, USA and Berlin-Brandenburgische Akademie der Wissenschaften, Berlin, Germany

Ontological research has focused largely on conceptual categories such as entities and event nominals encoded by nouns. In contrast, relatively little work has been devoted to the ontological properties of verbs and the concepts they refer to. Nouns may function as arguments of verbs and the concepts they express are thus related. Conversely, the ontological status of verbs can only be fully understood in the environment of their arguments.

In this paper, we distinguish three broad classes of English motion verbs structured around their syntactic properties and the semantics of their complements. Talmy (1985) demonstrates the centrality of the concepts MANNER and PATH in the lexicalization of motion verbs across languages. We propose a new distinction for carving up the motion verb lexicon, particularly for manner-of-motion verbs like "amble" and "saunter", and inherently directed verbs such as "cross" and "bridge". We argue for a more fine-grained distinction of PATH and the associated GROUND. In particular, we provide syntactic and semantic evidence for the introduction of two subordinate concepts to GROUND, namely OBSTACLES and REGIONS. Obstacles are selected for by inherently directed verbs, while manner-of-motion verbs select for Regions.

Syntactically, as shown in (1) and (2), Obstacles, but not Regions, behave like regular direct objects: they can undergo passivization and middle formation. Another difference between the two types occurs with "-ing" nominalization, as shown in (3).

1. a. The river was crossed/bridged
   b. *The streets were ambled/sauntered
2. a. This river bridges/crosses easily
   b. *The new boardwalk ambles/saunters easily
3. a. The crossing/bridging of the river
   b. *the ambling/sauntering of the streets

Note, a few verbs such as "swim", "walk" and "scramble" exhibit polysemy with respect to the Obstacle/Region distinction. In other words, they may have both inherent motion and manner interpretations.

Obstacle-taking verbs, unlike verbs selecting for Regions, are compatible with measure or distance phrases. Aspectually, events involving Obstacles are temporally bounded accomplishments, while those involving Regions are unbounded activities. For example, verbs like "roam" and "prowl" express random motion without reference to an endpoint or goal. The objects of these verbs are always Regions.

Our distinction further refines Levin's (1993) manner of motion class in picking out a subclass of "shape-of-trajectory" verbs such as "zigzag" and "crisscross". We show that these verbs can be classified as Region verbs. Another Levin class, dubbed "Verbs that are Vehicle Names" can be shown to be heterogeneous: some members are Obstacle verbs, others Region verbs.

In summary, we distinguish two broad classes of verbs structured around their syntactic properties and the semantics of their complements. Obstacle-taking verbs such as "cross" and "bridge" are elaborations of a more basic verb, TRAVERSE. Verbs like "amble" and "saunter" are specializations of the generic verb TRAVEL, expressing method of locomotion or a mode of transportation.

Levin, B. (1993). English Verb Classes and Alternations: A Preliminary Investigation. University of Chicago Press.

Talmy, L. (1985). Lexicalization Patterns: Semantic Structure in Lexical Forms. In Shopen, T., ed., Language Typology and Syntactic Description, vol. 3. Cambridge University Press.