WordNet
Where are the textbook libraries algs4.jar?
If you took Algorithms Part I, you should already have them installed.
Otherwise, you can download them from
the booksite.
This page also contains links to all of the APIs.
What should sap(), ancestor(), or outcast()
return if there is a tie for shortest ancestral path or outcast?
The API does not specify, so you are free to return any such
ancestor or outcast.
Do I need to throw exceptions explicitly with a throw statement?
No, it's fine if they are thrown implicitly, e.g., you can rely on any
method in
Digraph.java
to throw a java.lang.IndexOutOfBoundsException
if passed a vertex argument outside of the prescribed range.
A good API documents the requisite behavior for all possible arguments,
but you should not need much extra code to deal with these corner cases.
Can I read the synset or hypernym file twice? No, file i/o is very expensive so please read each file only once and store it in an appropriate data structure.
Any advice on how to read in and parse the synset and hypernym data files?
Use the readLine() method in our In library to read
in the data one line at a time.
Use the split() method in Java's String library
to divide a line into fields. You can find an example using split() in
Domain.java.
Use Integer.parseInt()
to convert string id numbers into integers.
Which data structure(s) should I use to store the synsets, synset ids, and hypernyms? This part of the assignment is up to you. You must carefully select data structures to achieve the specified performance requirements.
Do I need to store the glosses? No, you won't use them on this assignment.
Can I use my own Digraph class?
No, it must have the same API as our
Digraph.java
class; otherwise, you are changing the API to the SAP constructor (which takes a
Digraph argument). Do not submit Digraph.java.
What is the root synset for the WordNet DAG?
38003,entity,that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
Can a noun appear in more than one synset?
Absolutely. It will appear once for each meaning that the noun has.
For example, here are all of the entries in synsets.txt
that include the noun word.
35532,discussion give-and-take word,an exchange of views on some topic; "we had a good discussion"; "we had a word or two about it" 56587,news intelligence tidings word,new information about specific and timely events; "they awaited news of the outcome" 59267,parole word word_of_honor,a promise; "he gave his word" 59465,password watchword word parole countersign,a secret word or phrase known only to a restricted group; "he forgot the password" 81575,word,a string of bits stored in computer memory; "large computers use words up to 64 bits long" 81576,word,a verbal command for action; "when I give the word, charge!" 81577,word,a brief statement; "he didn't say a word about it" 81578,word,a unit of language that native speakers can identify; "words are the blocks from which sentences are made"; "he hardly said ten words all morning"
Can a synset consist of exactly one noun? Yes. Moreover, there can be several different synsets that consist of the same noun.
62,Aberdeen,a town in western Washington 63,Aberdeen,a town in northeastern South Dakota 64,Aberdeen,a town in northeastern Maryland 65,Aberdeen,a city in northeastern Scotland on the North Sea
I'm an ontologist and I noticed that your
hypernyms.txt file contains both is-a and
is-instance-of relationships.
Yes, you caught us. This ensures that every noun (except entity)
has a hypernym. Here is an article on the
subtle distinction.
What assumption can I make about the digraph G passed to the SAP constructor? It can be any digraph, not necessarily a DAG.
Should I re-implement breadth-first search in my SAP class?
It depends. You are free to call the relevant methods in
BreadthFirstDirectedPaths.java.
However, you can improve performance by several orders of magnitude by implementing it yourself, optimizing
it for repeated calls with the same digraph. (See the optional optimization section below.)
If you choose to implement your own version of BFS, give it a different name, e.g.,
DeluxeBFS.java, and submit it.
I understand how to compute the length(int v, int w) method
in time proportional to E + V
but my length(Iterable<Integer> v, Iterable<Integer> w)
method takes time proportional to a × b × (E + V),
where a and b are the sizes of the two iterables. How can
I improve it to be proportional to E + V?
The key is using the constructor in BreadthFirstDirectedPaths that
takes an iterable of sources instead of using a single source.
Is a vertex considered an ancestor of itself? Yes.
How can I make the data type SAP immutable?
You can (and should) save the associated digraph in an instance variable.
However, because our Digraph data type is mutable,
you must first make a defensive copy by calling the copy constructor.
Some examples. Here are some interesting examples that you can use in your code.
worm and bird is "animal animate_being beast brute creature fauna"
with a distance of 5. Other common ancestors of worm and bird
with longer distances are: "person individual someone somebody mortal soul"
and "instrumentality instrumentation".
The synsets that contain worm are:
81679 worm 81680 worm 81681 worm 81682 worm louse insect dirt_ball
The synsets that contain bird are:
24306 bird 24307 bird fowl 25293 boo hoot Bronx_cheer hiss raspberry razzing razz snort bird 33764 dame doll wench skirt chick bird 70067 shuttlecock bird birdie shuttle
municipality has two paths to region.
municipality -> administrative_district -> district -> region municipality -> populated_area -> geographic_area -> region
individual and edible_fruit
have several different paths to their common ancestor
physical_entity.
individual -> organism being -> living_thing animate_thing -> whole unit -> object physical_object -> physical_entity person individual someone somebody mortal soul -> causal_agent cause causal_agency -> physical_entity edible_fruit -> garden_truck -> food solid_food -> solid -> matter -> physical_entity edible_fruit -> fruit -> reproductive_structure -> plant_organ -> plant_part -> natural_object -> unit -> object -> physical_entity
(distance = 23) white_marlin, mileage (distance = 33) Black_Plague, black_marlin (distance = 27) American_water_spaniel, histology (distance = 29) Brown_Swiss, barrel_roll
entity.
Ambrose Saint_Ambrose St._Ambrose
synsets.txt is 119,188.
SAP, WordNet, and Outcast.
SAP.
First, think carefully about designing a correct and efficient
algorithm for computing the shortest ancestral path.
Consult a staff member if you're unsure.
In addition to the digraph*.txt files,
design small DAGs to test and debug your code.
Modularize by sharing common code.
synsets.txt
and hypernyms.txt.
Don't worry about storing the data in any data structures yet.
Test that you are parsing the input correctly before proceeding.
WordNet. Divide the constructor into
two (or more) subtasks (private methods).
synsets.txt file and build
appropriate data structures.
Record the number of synsets for later use.
hypernyms.txt file and build a
Digraph. For this input, your digraph should have
82,192 vertices and 84,505 edges (but do not hardwire either of
these numbers into your program because it must work for
any valid input files).
Implement the remaining WordNet methods.
Implement Outcast.
There are a few things you can do to speed up a sequence of SAP computations on the same digraph. Do not attempt to do this or any of your own invention without thoroughly testing your code. You can gain bonus points for correctly implementing some of these optimizations but you risk losing more points than you can gain if you introduce bugs that render your solution no longer correct.
length() and
ancestor() queries.