Word ladder facts for kids

Word ladder (also known as Doublets, word-links, change-the-word puzzles, paragrams, laddergrams, or word golf) is a word game invented by Lewis Carroll. A word ladder puzzle begins with two words, and to solve the puzzle one must find a chain of other words to link the two, in which two adjacent words (that is, words in successive steps) differ by one letter.

Rules

The player is given a start word and an end word. In order to win the game, the player must change the start word into the end word progressively, creating an existing word at each step. Each step consists of a single letter substitution. For example, the following are the seven shortest solutions to the word ladder puzzle between words "cold" and "warm", using words from Collins Scrabble Words.

COLD → CORD → CARD → WARD → WARM

COLD → CORD → CORM → WORM → WARM

COLD → CORD → WORD → WARD → WARM

COLD → CORD → WORD → WORM → WARM

COLD → WOLD → WALD → WARD → WARM

COLD → WOLD → WORD → WARD → WARM

COLD → WOLD → WORD → WORM → WARM

Often word ladder puzzles are created where the end word has some kind of relationship with the start word (synonymous, antonymous, semantic...). This was also the way the game was originally devised by Lewis Carroll when it first appeared in Vanity Fair.

Some variations also allow the player to add or remove letters, and to rearrange the same letters into a different order (an anagram).

Five-letter word ladders

Donald Knuth used a computer to study word ladders of five-letter words. He believed that three-letter word ladders were too easy (although Lewis Carroll found six steps were required for APE to evolve into MAN), and that six-letter word ladders were less interesting, since relatively few pairs of six-letter words could be connected with a word ladder. Knuth used a fixed collection of 5,757 of the most common English five-letter words, excluding proper nouns. He determined exactly when two words of the collection had a word ladder between them via other words in the collection. Knuth found that most words were connected to each other, and he also found that 671 words of the collection did not form a word ladder with any other words. He called these words "aloof", because "aloof" is itself an example of such a word.

See also

In Spanish: Escala de palabras para niños