What3Words – The Algorithm

Spelling is the Achilles' heel of all word-based systems.

People who have trouble with spelling (such as non-native speakers of whatever language the words come from or children) may not be able to rely on word-based systems. Word-based systems are also going to be hampered by speakers of different accents.

Letter- and number-based systems are probably always going to be much more robust, especially when used with a standard phonetic alphabet[1]. There could even be a checksum letter/number to make the system even more robust. Unfortunately, such systems will never be as memorable or as easy to say as a few words (spelling issues aside).

[1] - https://en.wikipedia.org/wiki/NATO_phonetic_alphabet

Bingo. Either more words, or fewer grid squares (f.e. instead of 3x3m grid, a 4x4m grid). I truly don't understand why they thought they needed 3m (10ft) of precision: my home has something like 10 What3Words addresses (80 if you count the yard and the other side of the duplex!). The old outhouse at the family ranch has more than one!

IMO, they also should have built redundancy (some form of error checking at least) into the encoding.

Funnily enough I did that math the other day when this kicked off.

It comes out to 4th root of ((510.1 trillion)/9) which is ~2743.8

Where it gets interesting is that it's only ~4752 for 1mx1m cells :)

Another use for `Correct Horse Battery Staple` I guess.

I did one of these for fun at the beginning of the year, and ended up needing to spend way more time on the wordlist than I'd expected. In the end I felt that a list of 4096 words was a decent compromise between accuracy and is still fairly managable for trying to remove words that are too easy to mistake for each other. It lets you do everywhere on earth to slightly more accuracy than what3words in 4 words.

Something that what3words does is not have an obvious hierarchy of words (e.g. where the first one covers a larger area, and subsequent words home in). I didn't like that, but I understand why they do it - if a single word is going to cover a large area, you have to be extra careful that you don't choose something offensive for a particular region. By having no obvious structure, they get away with being less careful on the wordlist.

I originally planned to use the crypto bip39 wordlist but ultimately it proved not to be suitable. I talk a little about it https://wherewords.id/+about

Crypto wallets may use BIP39 protocol, it might be close to a 'standard'?

https://github.com/bitcoin/bips/blob/master/bip-0039.mediawi...

Edit: 2048 English wordlist is here https://github.com/bitcoin/bips/blob/master/bip-0039/english...

In addition to BIP39 cited below, the EFF also published some useful wordlists a few years ago... https://www.eff.org/deeplinks/2016/07/new-wordlists-random-p...

One has the nice property that all words have unique 3 letter prefix. But not as many in prefix list (1296) as their "long" list (7776).

That said I'm kinda partial to BIP39... first four letters are unique, and words are more uniform than EFF prefix list.

But it looks like GPS addressing schemes like w3w need a MUCH larger list by an order of magnitude.

> I just want to pull something into my project

My experimentation mostly lives here: https://github.com/kybernetikos/wherewords/tree/main/lib/wor...

If you're coding in JS, I'd use https://www.npmjs.com/package/verbal-id for 10bits, bip39 for 11 bits, and maybe my wordlist for 12 bits.

You're right that would be cool. I haven't done anything on it since the beginning of the year.

There is a small easter egg though - wherewords.id works with fewer than the four words, so for example, if you go to https://wherewords.id/system/festival/ you'll see it highlight a particular part of New York City, while https://wherewords.id/system covers a big part of New York State and Pennsylvania.

I think that £23m is just capital from issued shares. Anyway, it's certainly not viable. I guess it remains to be seen how long investors will keep on chucking money at it to keep it afloat.

Filing history, if anyone else is interested: https://find-and-update.company-information.service.gov.uk/c...

IIRC Daimler wanted to integrate w3w into their onboard navigation units.

Nelson is right. A bunch of us have played around with designing our own human friendly geohash scheme.

If you divide earth up into 4m x 4m cells using something like the S2 projection, you can uniquely address these using phrases of 3 words drawn from a database just under 32,000 words. The S2 projection ensures that the words in the higher levels of the hierarchy will change quite slowly. In most local contexts there will be only a single commonly repeated word. In a small number of more exceptional points there'd be just 2 or 3 unique values in use. So in practice you could use longer addresses and a smaller dictionary if you liked. This is probably a good idea for ergonomic reasons, as we can pick a set of words that are readily translated between languages, weed out any that are overly similar, etc.

I never uploaded the code anywhere, and it's on a laptop that died, but I busted out a toy version of the above in an afternoon a couple years ago just for fun. I used 4 word addresses and a database of about 2,500 of the most common english words.

W3W's entire value proposition is that they should earn a global rent off the use of addresses vs the above. It's absurd. And they intentionally avoid hierarchical organization of the addresses specifically to make it necessary to use their app/service to look crap up, which makes their service hilariously worse than the scheme described above.

With an S2 style hierarchy people will intuitively begin to recognize the common words in their living area at each level, and can use them in conversation without even consulting software. This is completely impossible with W3W's scheme.

The problem isn't figuring out a good scheme. Most of the people on this forum can manage that in a couple hours. The problem is the same with all other standardization efforts: getting a critical mass of people who give enough of a crap to use the standard.

This is an area where Google could ship something in maps and it'd have a decent chance of adoption outside of it. If you work on maps consider pitching a more ergonomic version of plus codes.

> I remembered the w3w immediately.

But in what situation is this useful? How is it more convenient or useful than a regular address? Even if you’re somewhere where there are no addresses, and you need to describe a location that has no other descriptive characteristics, isn’t it a lot easier to just drop a pin/bookmark on the map in your smartphone? Especially considering you can’t reasonably run the algorithm without a digital device of some kind.

> cant we just agree on an open w3w implementation.

They don't want that to happen, at least not an open source implementation. They want to be in the position of Pantone and colour.

Why 3 words? Why not 4?

Hi Ragi! My complaint with What3Words is 85% their proprietary business model. They are literally trying to convince less developed countries to adopt their system in lieu of developing their own addressing systems. So that What3Words can forever force that country and anyone sending mail to it to pay them fees. It is evil.

This is not theoretical; back in 2017 they were bragging at how they'd convinced the nations of Kiribati, Mongolia, Sint-Maarten, Côte d’Ivoire, Djibouti, Tonga, Nigeria and the Solomon Islands to use them as a national standard. I'm certain that the actual usage is exaggerated on their part but imagine if it were really true. Addressing is far too important to be held by a proprietary company. Addressing is a national service that countries should provide as part of being a nation, and there's a long history of countries developing addressing systems that does not rely on some predatory intellectual property system.

5% of my annoyance is What3Words pretends like they invented some brilliant new idea that's unique and should be IP protected. No, the idea is older than them. And the implementation is obvious to anyone with ordinary skill in the art of addressing. Anyone competent with GIS concepts can design a similar system in a few days' work. And there are many better alternatives.

The other 10% of my complaint is their static addressing model. It's not good that two houses nearby have completely different addresses; real addressing always has hierarchical names and there's a reason for that. There's also a problem using words in that they are localized to the country's language. That's better than forcing English everywhere but makes interoperability way more confusing. Finally there's all the problems people keep finding with their word lists; that's covered well by other writers so I won't go into it.

PS: I misspoke when I said Geohash is the oldest similar system. MGRS dates to the 1940s. There may be older ones, too.

A standard for global addressing should not rely on a proprietary algorithm or wordlist, as it means that there is no legal method for using the standard besides using (paying for) What3Words’ API. This fits the common definition of rent-seeking behavior.

This couples with the technological issues outlined in the article above. I believe the vitriol against W3W is fueled by the combination of rent-seeking behavior on a standard of poor technical quality.

I’m also bothered that one of the main use cases W3W’s marketing highlights is for specifying locations in emergencies, a totally non-commercial/public-good application. W3W presents itself convincingly to laymen as this sort of public-good open standard, but they’re just another startup with a proprietary product they’re hoping to monopolize.

Furthermore, there's a payola scheme behind the scenes, to make sure automakers implement it in their infotainment systems and stuff, which they hope will force others to license it.

It's a great idea, a mediocre implementation, and a set of business practices that make the antichrist jealous.

On top of that, their bloodthirsty pursuit of any criticism means that legitimate discussions of the system's flaws can't happen in the open. The lack of that criticism may have encouraged some services to adopt W3W without realizing its flaws, and there's already some hinting that such a flaw may have already interfered with actual rescue operations:

https://www.bbc.com/news/technology-56901363

Thankfully the rescue was able to proceed once they switched to another coordinate system, and that case didn't result in a fatality. How many other such cases are there? We might never know. The company may have literal blood on its hands at this point, but fixing the flaws would require discussing them first, which we can't do as long as they're empowered to shut down discourse.

The hate is because they patented it. It is a useful idea, but it would be far more useful if the algorithm and wordlist were public domain and didn't require a license to use it.

Doesn’t the plus code algorithm rely on tiling the globe with a space filling curve? I’d be surprised if that could be done simply.