61A Lecture 37
Friday, December 2
Friday, December 2, 2011
What is Computer Science?
Systems
Computer Vision
Artificial Intelligence
Planning
Graphics
Robotics
Security
Natural Language Processing
Networking
...
Programming Languages
...
2
Friday, December 2, 2011
Machine Translation
Target language corpus gives examples of well-formed sentences
I will get to it later
See you later
He will do it
Parallel corpus gives translation examples
I will do it gladly
You will see later
Yo lo haré de muy buen grado
Después lo veras
Machine translation system:
Source language
Yo lo haré después
NOVEL SENTENC
Model of
translation
Target language
I will do it later
E
3
Friday, December 2, 2011
The Syntactic Structure of Natural Language
Parallel corpus gives translation examples
S
S
NP
NP
VP
MD
PRP
VP
VP
MD
VB PRP ADV
PRP
VP
VB ADV
I will do it gladly
You will see later
Yo lo haré de muy buen grado
Después lo veras
Machine translation system:
S
S
ADV
Yo lo haré después
Model of
translation
ADV
I will do it later
4
Friday, December 2, 2011
A Translation System in 20 Minutes
Context-free grammars as a model of language generation
Large-scale linguistic annotations
Tree transformations
English
Yoda-speak
Help you, I can!
Yes! Mm!
When 900 years old you reach,
look as good, you will not. Hm.
5
Friday, December 2, 2011
A Context-Free Grammar Describes Generation
"Grammar"
S
S -> NP VP
NP -> PRP↓NP
NP
PRP
VP
VB
Grammar
refinement
VP -> VB
VP -> VB PRP↓VP
PRP ↓VP
"Lexicon"
I
know
you
PRP↓NP
PRP -> I
PRP -> you
VB -> know
VB -> help
PRP↓VP -> me
6
Friday, December 2, 2011
A Context-Free Grammar Describes Generation
"Grammar"
S
S -> NP VP
NP -> PRP
NP
VP -> VB
VP
VP -> VB PRP
PRP
VP -> MD VP
VP
MD
"Lexicon"
I
can
VB
PRP
PRP -> I
PRP -> you
help
you
VB -> know
VB -> help
A grammar can be learned from data (demo)
MD -> can
7
Friday, December 2, 2011
Left-Corner Parsing Builds Trees For Sentences
parse_next(S, 1)
"Grammar"
complete(S, (PRP i), 1)
complete(S, (NP (PRP i)), 1)
S -> NP VP
NP -> PRP
parse_next(VP, 2)
complete(VP, (VB know), 2)
complete(VP, (VP (VB know)), 2)
complete(S, (S ...), 1)
VP -> VB
VP -> VB PRP
Left corners
S
"Lexicon"
NP
PRP
i
VP
PRP -> I
PRP -> you
VB
know
VB -> know
you
VB -> help
8
Friday, December 2, 2011
Left-Corner Parsing Builds Trees For Sentences
parse_next(S, 1)
"Grammar"
complete(S, (PRP i), 1)
S -> NP VP
complete(S, (NP (PRP i)), 1)
NP -> PRP
parse_next(VP, 2)
VP -> VB
complete(VP, (VB know), 2)
complete(VP, (VP (VB know) (PRP you)), 2)
complete(S, (S ...), 1)
VP -> VB PRP
Left corners
S
"Lexicon"
NP
PRP
i
VP
PRP -> I
VB
PRP
know
you
PRP -> you
VB -> know
VB -> help
9
Friday, December 2, 2011