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Show HN: CryptoFinalFour – Tradable March Madness brackets as ERC-721 tokens (cryptofinalfour.com)
34 points by vincentchu 7 months ago | hide | past | web | favorite | 32 comments



This is actually really interesting when you're dealing with large pools.

Last year, I was in a pool with 10,000+ people and serious $ were on the line and I actively negotiated with other brackets to buy them, split ownership, etc.

A few questions/comments: - Would you also be able to sell a % of the bracket rather than just all of it? - Would you also build out tools to predict the current odds of the entries?


Technically the bracket could be owned by another contract rather than a normal account so in theory at least it's possible.


^^ this. The base contract allows only a single owner at a time, but you can end up with some pretty exotic ownership structures if you want ...


That makes sense - cool idea and definitely see the value if and when sports gaming becomes legalized...


I know next to nothing about this domain (sports...), but I guess you need to have the outcome of the matches to make this work? How is that information entered onto the blockchain? I guess there is a trusted party somewhere that acts like an oracle?


The smart contract has a method called updateState that allows a privileged address to update the brackets. That’s essentially an Oracle.

Aside: in the future where smart contracts are broadly usable, there needs to be some way (even centralized) to identify who’s trusted in such a contract and why you should trust them. In a normal office pool, it’s just Dave from accounting who runs the pool, but on the block chain that breaks down.


I was wondering how Augur got around the need for an oracle, since on that system (iiuc), one can create a prediction market around any publicly-observable outcome.

In centralized markets, one person determines the final market outcomes - which means there can be mistakes or outright manipulation. With Augur, we'll have thousands reporting on market outcomes using a one-of-a kind consensus based system and a unique token called REPutation. As a reporter, you'll report on events every two months and, in return, receive half of all fees in the system multiplied by the percent of REP you own.

via http://www.augur.net/


The answer is within your quote:

With Augur, we'll have thousands reporting on market outcomes using a one-of-a kind consensus based system and a unique token called REPutation. As a reporter, you'll report on events every two months and, in return, receive half of all fees in the system multiplied by the percent of REP you own.

So, what they are relying on is that multiple people reporting a particular event can avoid manipulation. This is something which is touched upon extensively in the book "Wisdom of the Crowds" [0].

But, they also know that people might not be interesting in reporting an event. So, they are provide an incentive which is something like a PoS mining system - you earn coins for reporting based on the percentage of coins you hold in your wallet.

Obviously, this can turn out to be very bad because crowd wisdom doesn't always work. But, it will be an interesting experiment. But, not an experiment worth a billion dollars - during early Jan.

[0] - https://en.wikipedia.org/wiki/The_Wisdom_of_Crowds


> In a normal office pool, it’s just Dave from accounting who runs the pool, but on the block chain that breaks down.

At scale for brackets, at least, there's a natural centralized authority to trust on the matter, which is the organization running the tournament (NCAA). The official records are theirs (for better and for worse) and any API they produce would be the authority of record. That they likely don't have such an API is a different, interesting problem.


Cool idea. Now I need to figure out what Cipher Browser is.


It’s a ethereum wallet/browser for distributed apps for mobile: https://www.cipherbrowser.com

Meta mask is the equivalent for chrome.

Cipher allows you to store some eth (or other ERC20) tokens on your phone, then use them to play with disturbed apps (like this one).


Cool. I'm in. This reminds me of another business idea that I had. A way to track down all the places I have ethereum stored. For loved ones. If I get hit by a truck. I don't understand why a unique browser is needed to store ethereum. Couldn't there just be an add-on for chrome/firefox/safari? Sorry, just talking out loud, I'm sure that's for a different post. Let the games begin!


There is a chrome extension that also acts as a wallet and allows you to interact with dApps called meta mask (https://metamask.io/)

Cipher is interesting because it's built for iOS/Android and allows people to use dApps on mobile (which Metamask can't do). In fact, CryptoFinalFour was designed for Cipher/mobile browsing first.


What is the oracle for telling the blockchain which team won? Do we just trust the person who wrote this contract?


Yes, have to trust the contract owner. You can imagine other scenarios where it’s some voting scheme, but generally feel like decentralized != trustless for a lot of things. You have to trust something at some point. What’s cool (imo) about smart contracts is that the terms (ie, code) are transparent and that enforcement of those terms is automatic.


This is an interesting experiment. I have been interested in building a derivative of sorts using tokens but never got around to learning ERC-721 token. Any good tutorials out there?


How do you get the actual results into the Blockchain? And how can we trust that part?


Link to the smart contract?



Can you please verify your contract on etherscan.io. It makes it clear that the code is what you say it is and people can interact with your smart contract too.

https://etherscan.io/verifyContract2?a=0x100cc2fa0ea14bf9b07...


I spent 10 minutes before work today trying to get it working, but couldn't do it. Any hints? The contract was developed using truffle and the solidity files for the contract, ERC721, and ERC165 interfaces are split apart.


https://etherscan.io/verifyContract?a=0x100cc2fa0ea14bf9b074... This page does not work for truffle deployed contracts. You will see a new Beta Source Code Contract Verifier link on that page (thats what I linked to above) , this will allow you to verify. Set the Optimized to No and Runs (Optimizer) to 0. This is how I got my hello world contract verified on the rinkeby test chain: https://github.com/Tri-Valley-Blockchain/blockchain-playgrou...


Is there an interface for trading these?


is this a sports sweepstakes but with cryptocurrency? is the contract itself implemented in Ethereum?


Not quite a sweepstakes- it’s just a standard March madness pool. The one interesting thing is that each bracket confirms to the ERC721 token standard, which means you can trade, buy, or sell brackets.

In that sense, using the ERC721 standard allowed me, a simple dev, to assertive/tokenize a simple digital good. Pretty fascinated by that possibility.

And yes, all written on ethereum. I can post the solidity source of people are interested.


Hi, looks great! Yes, can you please post the solidity source code? I've just started learning solidity last week, and I like any understandable real world example I can get my hands on. Thanks!



Awesome, much appreciated!


ERC721 is Ethereum token, yes.


IS this legal?


Not crypto related.

HN is a technical forum. Maybe 'March Madness on Ethereum' might be a better title / name.


Agree that “crypto” is generally short for “cryptography” and not “cryptocurrencies”— i myself have been annoyed by that in the past. But now that I’ve drunk the Kool Aide .... ;)




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