Charles Reid b45fda3052 | 1 år sedan | |
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output | 2 år sedan | |
.gitignore | 2 år sedan | |
LICENSE | 2 år sedan | |
README.md | 1 år sedan | |
diff_by_n.py | 1 år sedan | |
diff_by_one_fixed.py | 1 år sedan | |
distinct.py | 2 år sedan | |
euclidean_distance.py | 2 år sedan | |
get_words.py | 2 år sedan | |
letter_coverage.py | 2 år sedan | |
letter_coverage_dbg.py | 2 år sedan | |
lexico.py | 2 år sedan | |
near_palindromes.py | 2 år sedan | |
palindromes.py | 2 år sedan | |
reverse_lexico.py | 2 år sedan | |
sgb-words.txt | 2 år sedan | |
stats.py | 2 år sedan | |
tries.py | 1 år sedan |
This repository contains Donald Knuth’s GraphBase list of five-letter words,
as well as scripts to run various combinatoric experiments,
graph algorithms, and other algorithms to explore the
relationships among these words.
The list of words comes from [1] and is in the public domain.
A Python program that contains a method for getting all of the five letter words from a file,
and that’s about it.
Exercises 26-37 of Knuth’s Volume 4 Fascile 0 are intended as a warm up to get to know
the SGB five letter word list. Solutions to these exercises are listed below.
distinct.py
- computes the number of SGB words containing exactly k distinct letters.
diff_by_one_fixed.py
- (fixed 2019-03-09) computes the number of words in the SGB
that are off by a single letter in each position. An example is rover
and spuds
.
Each corresponding letter is only different by one: r -> s
, o->p
, and so on.
This uses recursive backtracking to generate possible matches for each word, and
uses a hash table to check for their existence in the original word set.
There are 38 such pairs in the SGB.
Also see Five Letter Words
on the charlesreid1.com wiki.
diff_by_n_fixed.py
- (added 2019-03-10.) using the corrected approach (above) to
computing differences by 1, this generalizes the calculation to words that are different
by a distance d
for each letter position.
Also see Five Letter Words: Part 4: Revisiting Diff by One
(blog post) on charlesreid1.github.io.
euclidean_distance.py
- computes the euclidean distance between two words. This uses
the traditional Euclidean distance definition but reinterprets distance to mean edit distance.
lexico.py
- find words that are sorted by lexicographic order (front to back, a-z).
palindromes.py
- look for five letter words that are either a palindrome, or a palindrome pair.
diff_by_n.py
- computes words in SGB that have an edit distance of n.
reverse_lexico.py
- variation on lexico.py
that finds words whose letters are in
reverse lexicographic order.
letter_coverage.py
- computes coverage of the alphabet (minimum number of words required
to provide X letters of the alphabet)
Knuth mentions, in the text, a couple of facts about how many words cover how much
of the alphabet. We authored a dynamic program to compute precisely this - given a
number of letters N from the alphabet, this program computes the minimum number of
words it takes to cover all N letters.
Also see Letter Coverage
page on the charlesreid1.com wiki.