This paper describes a corpus of situated multiparty chats developed for the STAC
project (Strategic Conversation, ERC grant n. 269427). and annotated for discourse
structure in the style of Segmented Discourse Representation Theory (SDRT; Asher &
Lascarides,2003). The STAC corpus is not only a rich source of data on strategic
conversation, but also the first corpus that we are aware of that provides discourse
structures for multiparty dialogues situated within a virtual environment. The corpus
was annotated in two stages: we initially annotated the chat moves only, but later
decided to annotate interactions between the chat moves and non-linguistic events from
the virtual environment. This two-step procedure has allowed us quantify various ways
in which adding information from the nonlinguistic context affects dialogue structure.
In this paper, we look at how annotations based only on linguistic information were
preserved once the nonlinguistic context was factored in. We explain that while the
preservation of relation instances is relatively high when we move from one corpus to
the other, there is little preservation of higher order structures that capture "the
main point" of a dialogue and distinguish it from peripheral information.