November 01, 2003

Discourse as turbulent flow

We've all known people like Sir Hector. If truth be told, most of us have probably been like Sir Hector sometimes.

Arthur Hugh Clough, 1819-1861
[lines 83-97]

Spare me, O mistress of Song! nor bid me remember minutely
All that was said and done o'er the well-mixed tempting toddy;
How were healths proposed and drunk 'with all the honours,'
Glasses and bonnets waving, and three-times-three thrice over,
Queen, and Prince, and Army, and Landlords all, and Keepers;
Bid me not, grammar defying, repeat from grammar-defiers
Long constructions strange and plusquam-Thucydidean;
Tell how, as sudden torrent in time of speat in the mountain
Hurries six ways at once, and takes at last to the roughest,
Or as the practised rider at Astley's or Franconi's
Skilfully, boldly bestrides many steeds at once in the gallop,
Crossing from this to that, with one leg here, one yonder,
So, less skilful, but equally bold, and wild as the torrent,
All through sentences six at a time, unsuspecting of syntax,
Hurried the lively good-will and garrulous tale of Sir Hector.

This offers a very different set of metaphors for discourse structure than the sedate stack discipline of Grosz and Sidner (1986), though Clough does suggest that more education and less alcohol should yield a more laminar flow of language, and therefore simpler structures.

Recently, Florian Wolf and Ted Gibson have questioned whether trees are an appropriate model for discourse coherence, and they support their case with a systematic study of AP Newswire and Wall Street Journal text, whose scribes are sober (or at least can hold their liquor better than Sir Hector), but still show about 12.5% crossed dependencies. More on this later...

[Update 11/03/2003: Florian has put .pdf form of their papers up here.]

Chafe's The flow of thought and the flow of language (1979) echoes the "flow" metaphor, but I don't know anyone who has picked up the "trick riding" idea :-). On the other hand, Lewis and Short tell us that Latin discursus (from discurro) meant "a running to and fro, running about, straggling", perhaps suggesting that a stack discipline is not necessarily always obeyed...

Posted by Mark Liberman at November 1, 2003 06:24 AM