1 Recursive Transition Networks Allen ’ s Chapters 3 J&M ’ s Chapter 10

2 Recursive Transition Networks

3 RTN Arc Types

4 The metal can was dark blue

5 1 The 2 metal 3 can 4 was 5 dark 6 blue 7

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7

8

9 Augmented Transition Networks Allen ’ s Chapters 4 J&M ’ s Chapter 20

10 Augmented Transition Networks An augmented transition network (ATN) is a recursive transition network that can perform tests and take actions during arc transitions. An ATN uses a set of registers to store information. A set of actions is defined for each arc, and the actions can look at and modify the registers. An arc may have a test associated with it. The arc is traversed (and its action is taken) only if the test succeeds. When a lexical arc is traversed, it is put in a special variable (*) that keeps track of the current word.

11 An ATN for NP

12 An ATN for S

13 1 the 2 dog 3 saw 4 Jack 5

14 An ATN Grammar for Simple Declarative Statements

15 The NP Network

16 The PP Network

17 Register Presetting Register Presetting  Parameter Passing vp:inf Mary wants to have a party. _np_vp:inf Mary wants John to have a party. Register VFORM of VP Graph should be preset to inf