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What is it? | How do I use it? | ...Why | See also
It's a grammar fragment written in Prolog to play with the idea of sentences consisting of only the word 'buffalo'.
It draws snazzy ASCII syntax trees thanks to Dr. Christoph Lehner's Prolog Tree Drawing Program.
Get SWI-Prolog, and call it like this:
$ swipl -s chris.pl buffalo.pl
You can generate sequences of "buffalo" with the seq_pow/3 predicate:
?- seq_pow([buffalo],3,Seq).
Seq = [buffalo, buffalo, buffalo] .
Parse it as a sentence:
?- parse_buffalo_n_s(3, Tree).
Tree = s(np(n(buffalo)), vp(v(buffalo), np(n(buffalo)))) .
Draw the parse tree:
?- draw_buffalo_n_s(3).
s
_____|_____
/ \
np vp
| ___|___
| / \
n v np
| | |
| | |
buffalo buffalo n
|
|
buffalo
With longer buffalo-sentences, you can press ; to step through all the possible parses:
?- draw_buffalo_n_s(5).
s
_______|______
/ \
np vp
| ______|_____
| / \
n v np
| | ____|___
| | / \
buffalo buffalo n cp
| ___|___
| / \
buffalo c s
| ____|___
| / \
e np vp
| ___|___
| / \
e v np
| |
| |
buffalo n
|
|
buffalo
true ;
s
_______|______
/ \
np vp
| ______|______
| / \
n v np
| | _____|____
| | / \
buffalo buffalo n cp
| _____|____
| / \
buffalo c s
| _____|____
| / \
e np vp
| __|__
| / \
n v np
| | |
| | |
buffalo buffalo e
true ;
s
_______________|_______________
/ \
np vp
____|___ ___|___
/ \ / \
n cp v np
| ___|___ | |
| / \ | |
buffalo c s buffalo n
| ____|___ |
| / \ |
e np vp buffalo
| ___|___
| / \
e v np
| |
| |
buffalo n
|
|
buffalo
true ;
s
_______________|______________
/ \
np vp
_____|____ ___|___
/ \ / \
n cp v np
| _____|____ | |
| / \ | |
buffalo c s buffalo n
| _____|____ |
| / \ |
e np vp buffalo
| __|__
| / \
n v np
| | |
| | |
buffalo buffalo e
true ;
s
_________|________
/ \
np vp
___|___ _____|_____
/ \ / \
adj n v np
| | | ___|___
| | | / \
buffalo buffalo buffalo adj n
| |
| |
buffalo buffalo
true ;
false.
You can also ask it to find the smallest n such that buffalon is a grammatical sentence:
?- min_n_for_s(N).
N = 3.
I was in a boring 3-hour class with no wifi.
- buffaloe, my friend Omar Rizwan's web port of this program
- Wikipedia on "Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo"
- Prolog and Natural-Language Analysis by Fernando C. N. Perreira and Stuard M. Shieber (pdf)
- SWI-Prolog
- the Prolog Wikibook, particularly the chapter on Definite Clause Grammars
- Dr. Christoph Lehner's Prolog Tree Drawing Program
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