 Yes, so It's yeah Ethereum is so great because with this with with Ethereum we now have this awesome Turing complete world computer and Because it's Turing complete it can do anything other programs can also do and This means smart contracts can now verify Solidity source code by just Recompiling it. They can analyze the stock market. They can verify state transitions in Private chains, which means you have chains that connect to each other They can evaluate neural networks and thus you have artificial intelligence on the blockchain And this in turn means that smart contracts can improve their own code by analyzing it And we can even do fully homomorphic privacy preserving elliptic curve CK snark mix of stuff whoo But yeah, I mean you all know that this is not really true because These smart contracts are really expensive and they need a lot of gas Next slide, please Yeah okay so Yeah, these tasks are too expensive and they won't fit into a block and then the the usual thing what you do is you you go off-chain this means There's a task giver a smart contract that asks some Program to be executed and Then there are workers which register with the system and compute the solution off-chain and Yeah, the problem is if two workers submit different solutions then you some somehow have to Decide which is the correct solution and the easiest thing to do there is just take the majority solution So the solution that has most Workers submitting it That is not really Stable there are easy ways to exploit that especially if it's easy to add new workers and the question is can we do better and This now comes to the the true bit project or in general Interactive verification of off-chain solutions or off-chain computations And it's a cooperation with a loyal Lou and Jason torch who wrote a paper about that Lloyd will also give a talk. I think tomorrow about or yente and The the general framework was already published in 2011. So this general interactive verification mechanism, but we want to Take this mechanism and and put it on the blockchain and add a proper Crypto-economic incentivization to Yeah, to do that and the the idea is to Achieve Similar trust levels as direct on-chain computations would would do but at a fraction of the cost So this is basically about a way how to scale the blockchain because you can take expensive computations off-chain This is so as in all these approaches. We've also seen it in the previous talk about state channels. It always has a Yeah, a Privacy component too, but it's not 100% safe. So we're focusing on the scalability here mostly and How does to it work? So we still have the same framework where we have a task giver that Publishes a task and then workers submit solutions, but now we don't take the majority solution instead We allow solutions to be challenged. So if two workers do not agree on the solution then the Yeah, the so-called verification game starts and The verification game is built in a way so that the honest actor will always win it There's there's no way that the honest actor can lose it and No, not yet, please and so it's also really cheap because the only on-chain part is that You only have to store hashes and then at the end of the whole process. You have to do a tiny computation step and yeah, this means Because the the the honest actor always wins you don't have a 51% attack But an 100% attack you have to all the the workers have to collude for it to fail There's a small fine print all those so we have to assume that Transactions are processed in time, which means we need a censorship resistant blockchain Which is not and we need an upper bound on the on the delay for a transaction to be processed Okay, how does the verification game work in detail? Let's assume. We have a computation with 1 million steps and at each of these steps the parties can be a mercenary of the full memory and then they Okay, they don't have to can be did it every step at a certain step. Sorry, and it works as follows. So Slow slowly, please So we have a step one and step one million they have the same input but different outputs and then We then the smart contract takes a look at the at the middle point and asks again for the root hashes and Next please and there we see the root hashes are still the same and what we're looking for is a single step where Both parties agree on the previous root hash, but they disagree on the next root hash and Because they agree here on the middle point, but they disagree at the end then there in this Yeah, in the right half there must be such a point so we again ask in the middle of the right half And there they disagree and yeah, and so on we again ask in the middle of the Yeah, yeah, so yeah, and this continues a bit and in this case Yeah, we found a Certain step where the previous root hash is the same but the the following root hash is different Next slide, please. Yeah, and it so in this case it took 20 rounds for 1 million steps and After we have found this single step All the information is published to the smart contract and It verifies this single step. So Access to memory is used via via Merkel proofs. Of course. So this is really really cheap Okay So 20 rounds sounds so 20 rounds in comparison to 1 million steps sounds Really good, but the problem is that we have to do this on-chain. It does not work off-chain because the two parties have conflicting incentives and this means it takes at least 20 blocks But there are techniques to further reduce this and more importantly We have this verification game But because of the fact that the honest actor will always win it it will never be played at so at least so if you lose it, you of course have to pay a fine you have to you lose you lose your deposit and So there's a great disincentive to even try it and you can of course try it, but it will cost a lot of money Yeah specific numbers if you take a look at a one-hour computation of four gigahertz processor you get roughly 14 times 10 to the 12 steps and If there's a disagreement then you There's a protocol that finds the cheater in 10 rounds and in each round you have roughly 600 bytes of messages Yeah, okay next slide please so How do you practically use it? The idea is that the tasks are implemented in in cc++ or rust so anything that can be compiled via LLVM and We use a special back-end called Lanai the reason is that Lanai is a very very simple virtual machine or yeah, not a virtual machine, but a very very simple machine and It's easy to implement this single step as a smart contract and So if you have this task then so then you kind of post the source code of it Into the system and you provide a fee and then workers can compile it to Lanai execute it and Yes, I've been to the solutions a Potential bonus that will come out of the system is that we can have swarm as a real actual file system for smart contracts so you can have smart contracts and Yeah, just regularly open files read and write and so on Okay, I think there's one more slide Yes, so the current state of implementation of this project is that Yeah, we have some proof of concept code We're now working on the the actual incentive and penalty structure and we're looking for some research grants in that area and For the implementation we we successfully apply to Wang Xiang for a Wang Xiang blockchain labs grant thank you for that and Yes, so That's the progress so far. Okay. Yeah, thank you