Presentation on theme: "1 Dependency structure and cognition Richard Hudson Depling2013, Prague."— Presentation transcript:
1 Dependency structure and cognition Richard Hudson Depling2013, Prague
2 The question What is syntactic structure like? –Does it include dependencies between words (dependency structure)? –Or does it only contain part-whole links (phrase structure)? Shelookedafterhim after him She looked after him
3 Relevant evidence: familiarity University courses teach only one approach. School grammar sometimes offers one. –Usually dependency structure –even in the USA Reed-Kellogg sentence-diagramming –especially in Europe –and especially in the Czech Republic!
4 What Czech children do at school blossomed out kingcups by stream near yellow Jirka Hana & Barbora Hladk á 2012
5 or even …
6 Relevant evidence: convenience Dependency structure is popular in computational linguistics. Maybe because of its simplicity: –few nodes –little but orthographic words Good for lexical cooccurrence relations
7 Relevant evidence: cognition Language competence is memory Language processing is thinking Memory and thinking are part of cognition So what do we know about cognition? A. Very generally, cognition is not simple –so maybe syntactic structures aren't in fact simple?
8 B. Knowledge is a network me Gaynor Lucy Peter John Gretta Colin
9 C. Links are classified relations person woman man relative parent child mother father is-a
10 D. Nodes are richly related me Gaynor Lucy Peter John Gretta Colin m s m f f d gf b b w h s s s s
11 E. Is-a allows default inheritance Is-a forms taxonomies. – e.g. 'linguist is-a person', 'Dick is-a linguist' Properties 'inherit' down a taxonomy. But only 'by default' – exceptions are ok. – e.g. birds (normally) fly –but penguins don't.
13 Cognitivism 'Cognitivism' –'Language is an example of ordinary cognition' So all our general cognitive abilities are available for language –and we have no special language abilities. Cognitivism matters for linguistic theory.
14 Some consequences of cognitivism 1.Word-word dependencies are real. 2.'Deep' and 'surface' properties combine. 3.Mutual dependency is ok. 4.Dependents create new word tokens. 5.Extra word tokens allow raising. 6.But lowering may be ok too.
15 1. Word-word dependencies are real Do word-word dependencies exist (in our minds)? –Why not? –Compare social relations between individuals. What about phrases? –Why not? –But maybe only their boundaries are relevant? –They're not classified, so no unary branching.
16 Punctuation marks boundaries At the end of the road, turn right. Not: –At the end of the, road turn right. –At the end, of the road turn right. –At the end of the road turn right, How do we learn to punctuate if we can't recognise boundaries?
17 No unary branching If S NP + VP, then: S NP VP N V Cows moo. Cows moo. N V But if a verb's subject is a noun:
18 2. 'Deep' and 'surface' properties combine. Dependencies are relational concepts. Concepts record bundles of properties that tend to coincide –e.g. 'bird': beak, flying, feathers, two legs, eggs –'mother': bearer, carer So one dependency has many properties: –semantic, syntactic, morphosyntactic –e.g. 'subject' ….
19 'subject' The typical subject is defined by meaning –typically 'actor' or … word order and/or case –typically before verb and/or nominative agreement –typically the verb agrees with it status –obligatory or optional, according to finiteness
20 So … Cognition suggests that 'deep' and 'surface' properties should be combined –not separated They are in harmony by default –but exceptionally they may be out of harmony –this is allowed by default inheritance
21 3. Mutual dependency is ok. Mutual dependency is formally impossible in standard notation And is formally impossible in phrase structure theory So if it exists, we need to –resist PS theory –change the standard notation
22 Mutual dependency exists I wonder who came? Who is subject of came, –so who depends on came. But who depends on wonder and came can be omitted: –e.g. Someone came – I wonder who. So came depends on who.
23 Standard notation A B B A A 'dominates' B so A is above B so B cannot 'dominate' A
24 4. Dependents create new word tokens. General cognition: –every exemplar needs a mental node. –no node carries contradictory properties. –so some exemplars need two nodes. E.g. when we re-classify things. –NB we can remember both classifications
25 What kind of bird? bird blackbird B B* ? mate
26 And in language … word LIKE-verb like ? subject I like* NB like* is a token of a token
27 The effect of a dependent When we recognise a dependent for W, we change W into a new token W*. The classification of W* may change. W* also has a new meaning –normally a hyponym of W –but may be idiomatic If we add dependents singly, this gives a kind of phrase structure!
28 typical French house HOUSE house meaning house house* house** French house meaning French house meaning typical French house meaning typical
30 5. Extra word tokens allow raising. rains subject it keeps it* raining subject it subject predicative
31 Raising in the grammar A A* C B higher parent lower parent shared A* is-a A, so A* wins.
32 6. But lowering may be ok too. Raising is helpful for processing –the higher parent is nearer to the sentence root. But sometimes lowering is helpful too –e.g. if it allows a new meaning-unit. Eine Concorde gelandet ist hier nie. a Concorde landed has here never. A-Concorde-landing has never happened here.
33 German Partial VP fronting gelandet ist hier nie Eine Concorde Eine Concorde* higher parent lower parent lowered
34 Conclusions Language is just part of cognition. So syntactic dependencies are: –psychologically real –rich (combining 'deep' and 'surface' properties) –complex (e.g. mutual, multiple). And dependency combines with –default inheritance –multiple tokens