I published some proof-of-concept Python code today while thinking about the inner workings of Wordle. Plenty has already been written about the game itself, its origin and appeal, and some solvers have been written as well. While my verbal brain super appreciates that, I’ve been doing a lot of Sudoku lately and the similarities in problem solving were fascinating. I got thinking really hard about how Wordle is put together from a math and probability standpoint.
What are the building blocks?
Wordle combines elements of a lot of games I enjoy — Mastermind, Wheel of Fortune, crosswords, and so on. But it’s really none of these, and that’s what makes it so interesting.
Superficially, it seems most similar to Mastermind. But with Mastermind, all potential combinations are equally likely, in theory, anyway. When playing against a human opponent, they may choose patterns they expect the player to fail to think of, and there’s some Roshambo-like strategy in faking someone out. Unlike Wordle, though, no one agrees ahead of time that only certain patterns are acceptable. In fact, there’s no way (apart from Sudoku and its variants, more on that later) to achieve that ahead of time except on something like a language corpus. So there are immediately interesting constraints that everyone can understand without a complicated ruleset.
It’s also like Hangman or Wheel of Fortune in one interesting way. Obviously neither of those games have the “not in this position” mechanic, but they do have another thing that other word games are less likely to have, leading to the thing I find really interesting about this game.
Negative information
Wordle is interesting because even guessing words that don’t match at all provides useful information about what does remain. Wheel of Fortune and Hangman have this concept, in that you know some things that won’t fill the available letters, This is the source of the humor for most of the Wheel of Fortune “fail” videos — a lot of times the contestant’s guess can’t be accurate, because it contains letters that have already been guessed.
Wordle has another interesting feature that tripped me up in designing the solver — you don’t know how many of a given letter there are unless you guess that many copies. In Wheel of Fortune, naming a letter immediately places all of those letters and by definition you know there are no more. Some of the harder Wordle solves result from needing to guess a double letter — and this is also why you could still run out of turns while guessing entirely on negative information.
However, consider the following sequence. The answer is NYMPH, which conveniently has no always-vowels.
READS⬛⬛⬛⬛⬛ 698 possibilities-
FRUIT⬛⬛⬛⬛⬛ 123 possibilities BLOCK⬛⬛⬛⬛⬛ 2 possibilities
The only words that fit these criteria are NYMPH and PYGMY — despite us never even guessing a single letter in any position! I wouldn’t even use the latter word in casual speech, so there’s only one real answer here. We derived this entirely through negative information.
Questions
Ultimately, what drove my interest is that it seems to be totally possible to get any given word in six guesses. Is that really the case? Are there sequences that you could reasonably guess with perfect information that wouldn’t get you there? What if you just pick a random or naive strategy and apply it blindly?
Rather than solving single words on a daily basis, I want to solve all the words. I’d love to understand the nooks and crannies of the English language that create really absurd patterns, like guessing NYMPH with no correct letters. I also wonder how this extends to longer patterns — does the game get harder, and then easier at higher levels? How difficult could it be to come up with a 15 letter word when there are so few to choose from?
As with many things, the creator seems to have hit on something that works really well — 5 letters in 6 guesses. What kind of tuning could be done to “prove” this is an optimal combination of a certain difficulty? Can you make it harder or easier (aside from the perfect knowledge aspect embodied in Wordle’s “hard mode”)? As I mentioned above, are there words that are just harder or easier depending on your strategy?
I left a couple of exercises for me or the reader to continue with in the readme — reproduced here:
- How “good” is a given guess against the current word? Against all Wordle words? Against any English word?
- What strategies are most effective across these sets?
- How “hard” is this game? What’s the average tree depth to get to a single word?
- How many ambiguous words have the same results right up to the solution (i.e., LIGER-TIGER)? What’s the maximum tree depth of ambiguous words?
- Can naive solvers win every time with 6 guesses? What’s the min/max for any given algorithm?
- What words minimize initial guesses? (Cracking the Cryptic suggested RISEN/OCTAL to cover top letter frequencies. Tom’s solver produced RAISE as the best first guess.)
No doubt someone else will do this work before I have a chance to get to all of it! If you’re one of those people, please take my scripts with my blessing and let me know how it goes!