 Hi everyone, this is an abstract talk for our paper lobster around if they're actually their leader election. So, this is me and this is a long, we need to decide who will go present the paper at crypto conference. Since we're in different city we decide to do bombs coin toss protocol on the blockchain. If the output is zero them a long ways and he will go. Otherwise, I will go present the paper. So, we each choose a random bit and post the commitments of the random bit on the blockchain. If you're not familiar with blockchain you can just think of it as a public bulletin board. So, after we post the commitments everyone can see it. After we post the commitments, we each open our random bit and post the opening from blockchain. Let's say my bid is zero in a long speed is one, then the output would be the extra of these two bits, which is one so I went and here I am. However, a long really wants to go to the beach in Santa Barbara. So after I post my beat on the blockchain he knows he's going to lose the game if he opens his bit. What if he refused to open his commitments. In this case, I just automatically wins an output is still one. So this is the famous bombs coin toss protocol. And it guarantees that a strategic player like even cannot bias the output towards his preference. Only in a coin toss protocol, we want to toss a uniformly random coin. The fairness notion considered in traditional crypto literature is called strong fairness or unbiased ability which requires that a strategic player cannot bias the output was either direction. Fortunately, this is trying to be impossible against more than half size collision by cleave in 1986. But we just saw that bombs coin toss protocol achieves some fairness, which is more of a game theory favor. It guarantees that a strategic player cannot benefit itself by deviating from the protocol nor can it harm an honest individual. A natural question to ask is what if we generalize to money party. As you might have seen our paper has four co authors. So when it comes to multiple parties, we have a leader election problem that elected leader from and players. The winner gains utility one and it takes all the other just in utility zero. So some of the players say Eileen and you know, they may form a coalition and they want to bias the output towards their favor. In leader election still we also care about the game theoretic fairness, we want to guarantee that no coalition can increase it's expected utility, and no coalition can harm any honest individual. One thing is why do we care about this, because strong fairness is impossible against half size coalition. However, in many decentralized applications, for example, voting on blockchain, many pseudonyms may be controlled by the same entity, and these pseudonyms will coordinate together and they may deviate from the protocol to gain benefit. I think it's very likely that these pseudonyms form a majority sized coalition. So we do need some meaningful fairness notion that it's achievable against a module, but majority size coalition, and game theoretic fairness is exactly such a notion that is likely we've heard that strong fairness yet still meaningful and super for decentralized applications. Actually, the attack I just mentioned with a lot of pseudonyms is a real world attack that just happens a few days ago. So previous work have shown that if we're willing to use login rounds, we can achieve perfect game theoretic fairness against arbitrary sized coalition. And if we're willing to sacrifice a little bit fairness but just requiring approximate fairness which says okay a coalition cannot increase their utility by too much. Then we can tolerate a one mind small one and sized coalition. But what if we want to achieve smaller run complexity. Can we do smaller than lock lock and rounds can we still achieve meaningful fairness within small or lock lock and runs. In this work we give an affirmative answer. We give a lock star run approximate game theoretically fairly your election against say point nine and sized coalition. And in the full talk we'll talk about how we get this result, and we'll give a fully parameterized result about the run complexity and fairness parameter. Thank you.