Hoorcollege 3 Dependency trees

Question 1

Constituency tree

Answer 1

{{A, boy}, {saw, {a, girl}}, {with, {a, telescope}}}

Question 2

Dependency tree

Answer 2

• Directed acyclic graph
• Each edge is labeled with element of set relations R
• There is a unique lexical element from which there is exactly one
  directed path to any lexical vertex/node
• Usually this unique element is the root
• Each subtree also has a root

Question 3

Projectivity

Answer 3

• Projectivity arc: there is a path from head to dependent and every word that lies between
• Projective dependency tree: only consists of projective arcs

Non-projective: crosses another edge

Question 4

Transition-based parsing

Answer 4

Common method to find dependency tree of an input
* ARC standard / ARC eager algorithms
leftarc, rightarc, shift, reduce

Question 5

Oracle

Answer 5

Predicts the action based on current configuration

Question 6

Dependency parsers

Answer 6

• Spacy’s dependency parsers uses an arg-eager algorithm
• Dependency treebanks: large collections of trees

Question 7

Styles of dependencies

Answer 7

• Pargue dependency style
• Stanford dependencies
• Universal dependencies