Word ladder

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.

Lewis Carroll says that he invented the game on Christmas day in 1877. The first mention of the game in Carroll's diary was on March 12, 1878, which he originally called "Word-links", and described as a two-player game. Carroll published a series of word ladder puzzles and solutions, which he then called "Doublets", in the magazine Vanity Fair, beginning with the March 29, 1879 issue. Later that year it was made into a book, published by Macmillan and Co.

J. E. Surrick and L. M. Conant published a book Laddergrams of such puzzles in 1927.

Vladimir Nabokov alluded to the game using the name "word golf" in the novel Pale Fire, in which the narrator says 'some of my records are: hate—love in three, lass—male in four, and live—dead in five (with "lend" in the middle).'

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 solutions to the word ladder puzzle between words "cold" and "warm".

COLD → CORD → CARD → WARD → WARM

COLD → CORD → CORM → WORM → WARM

COLD → WOLD → WORD → WARD → 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).

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