# charlesreid1/five-letter-words

Experiments with five letter words.
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 Failed to load latest commit information. output .gitignore LICENSE README.md diff_by_n.py diff_by_one.py distinct.py euclidean_distance.py get_words.py letter_coverage.py lexico.py near_palindromes.py palindromes.py reverse_lexico.py sgb-words.txt stats.py

# five-letter-words

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.

## Get Words

A Python program that contains a method for getting all of the five letter words from a file, and that's about it.

## Warm Up Exercises

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.py` - computes the number of words in the SGB that are off by a single letter, shifted a single place. For example, "might" and "night" or "large" and "marge". There is a surprisingly large number of such pairs.

`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.

### Variations

`diff_by_n.py` - computes words in SGB that have an edit distnace of n.

`reverse_lexico.py` - variation on `lexico.py` that finds words whose letters are in reverse lexicographic order.

## Letter Coverage

`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.

# Sources

1. Knuth, Donald. The Stanford GraphBase: A Platform for Combinatorial Computing. New York: ACM Press, 1994. <http://www-cs-faculty.stanford.edu/~knuth/sgb.html>