Recursive Transition Networks

Recursive Transition Networks

Allen’s Chapters 3 J&M’s Chapter 10

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Recursive Transition Networks

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RTN Arc Types

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The metal can was dark blue

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

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

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

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

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Augmented Transition Networks

Allen’s Chapters 4 J&M’s Chapter 20

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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. 10

An ATN for NP

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An ATN for S

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the 2 dog 3 saw 4 Jack 5

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An ATN Grammar for Simple Declarative Statements

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The NP Network

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The PP Network

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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 17