A while ago, a strong and well‑known Chinese contestant achieved rank 1 in an AtCoder Regular Contest (ARC). Instead of receiving a significant rating increase, he was banned. I was quite shocked at that time, so I left a comment under the blog of that contest. I thought such an incident was merely an isolated case, but last night on Codeforces, a classmate of mine (CF handle: kongdechangjunkongde) was suddenly banned during a contest. I currently do not know the reason for his ban, but given his character, I believe it is highly unlikely that he cheated. Of course, if further investigation reveals that he did cheat, that is a different matter. Nevertheless, this has made me question the cheating review mechanisms of Codeforces and AtCoder – how exactly does the anti‑cheating system work?↵
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In the early stages of my competitive programming (OI) career, Codeforces' anti‑cheating system seemed very robust to me, capable of accurately identifying cheating. However, with the rapid advancement of AI, the system appears to be quite inadequate. Sometimes obvious cheaters are not detected, while innocent contestants who participate legitimately get banned. Of course, I will not make the mistake of "throwing out the baby with the bathwater" – an anti‑cheating system is definitely needed. But I think the administrators of Codeforces and AtCoder should also realise that the system can make false judgments, and it would be more reasonable to provide a dedicated appeal channel.↵
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Luogu, the most influential programming website in China, handles appeals quite well. The appeal rules on Luogu roughly require meeting one of the following conditions:↵
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1. The appeal is submitted by a high‑level contestant – corresponding to Codeforces, a Grandmaster (GM) or above can appeal on behalf of the accused.↵
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2. The contestant has a full video recording of the contest.↵
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3. Other cases that are clearly not cheating, such as mistakes made by the problem setter.↵
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Although many contestants criticised these rules as being too unreasonable and restrictive when they were first introduced, after being in effect for a long time, I have not seen many complaints about misjudgments.↵
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So I am wondering: is it feasible for Codeforces and AtCoder to provide an appeal channel for misjudged contestants?↵
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Translated by DeepSeek. The original Chinese text is as follows:↵
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由 deepseek 翻译，以下是中文原文：↵
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标题:CF和AT是怎么判断一个选手是否作弊了的？以及是否能够提供一个申诉渠道？↵
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正文：前段时间一位很有实力也很有名气的中国选手在ARC中斩获 rk1，结果他等来的不是大幅度上分，而是封号。当时我非常震惊，因此在 AT 那场比赛的blog下也有留言。我以为这样的现象仅仅是个例，但是昨天晚上的 CF，我的一位同学，CF 帐号是kongdechangjunkongde，在打比赛过程中突然被封号了。我目前不知道他被封禁的理由，但是我觉得以他的人品大概率上不可能作弊。当然，如果后续调查发现真的作弊了另说。但是这也让我对 CF 和 AT 的作弊审核机制产生了疑惑，反作弊系统到底是如何工作的？↵
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在我OI 生涯的前期阶段，CF 的反作弊机制在我看来非常有力，能够准确识别作弊现象。但是当AI发展迅速之后，反作弊机制显得非常力不从心。有时候很明显的作弊者未能被识别出，而没有作弊的，正常参赛的选手却被封号。当然，我不会犯因噎废食的错误，反作弊机制显然是要的。但是我想CF和AT的负责人也应该意识到反作弊机制是会误判的，应该提供一个专门的申诉渠道才更为合理。↵
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中国最有影响力的编程网站，洛谷，在申诉这件事情上就做得挺好。洛谷申诉的规则大致是以下条件满足其一：↵
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1. 申诉需要高水平选手，对应到 CF，可以是GM及以上选手代为申诉↵
2. 有全程录像↵
3. 其他一些，明显不是作弊的情况，比如出题人的一些失误操作↵
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虽然在申诉规则出来之时，大量的选手批判规则太不合理，有为难的成分，但是在实行许久之后，我并没有看到什么选手抱怨自己被误判了。↵
↵
所以我在想，CF 和 AT 为误判选手提供申诉渠道，是否具备一定的可行性呢？
↵
In the early stages of my competitive programming (OI) career, Codeforces' anti‑cheating system seemed very robust to me, capable of accurately identifying cheating. However, with the rapid advancement of AI, the system appears to be quite inadequate. Sometimes obvious cheaters are not detected, while innocent contestants who participate legitimately get banned. Of course, I will not make the mistake of "throwing out the baby with the bathwater" – an anti‑cheating system is definitely needed. But I think the administrators of Codeforces and AtCoder should also realise that the system can make false judgments, and it would be more reasonable to provide a dedicated appeal channel.↵
↵
Luogu, the most influential programming website in China, handles appeals quite well. The appeal rules on Luogu roughly require meeting one of the following conditions:↵
↵
1. The appeal is submitted by a high‑level contestant – corresponding to Codeforces, a Grandmaster (GM) or above can appeal on behalf of the accused.↵
↵
2. The contestant has a full video recording of the contest.↵
↵
3. Other cases that are clearly not cheating, such as mistakes made by the problem setter.↵
↵
Although many contestants criticised these rules as being too unreasonable and restrictive when they were first introduced, after being in effect for a long time, I have not seen many complaints about misjudgments.↵
↵
So I am wondering: is it feasible for Codeforces and AtCoder to provide an appeal channel for misjudged contestants?↵
↵
Translated by DeepSeek. The original Chinese text is as follows:↵
↵
由 deepseek 翻译，以下是中文原文：↵
↵
标题:CF和AT是怎么判断一个选手是否作弊了的？以及是否能够提供一个申诉渠道？↵
↵
正文：前段时间一位很有实力也很有名气的中国选手在ARC中斩获 rk1，结果他等来的不是大幅度上分，而是封号。当时我非常震惊，因此在 AT 那场比赛的blog下也有留言。我以为这样的现象仅仅是个例，但是昨天晚上的 CF，我的一位同学，CF 帐号是
↵
在我OI 生涯的前期阶段，CF 的反作弊机制在我看来非常有力，能够准确识别作弊现象。但是当AI发展迅速之后，反作弊机制显得非常力不从心。有时候很明显的作弊者未能被识别出，而没有作弊的，正常参赛的选手却被封号。当然，我不会犯因噎废食的错误，反作弊机制显然是要的。但是我想CF和AT的负责人也应该意识到反作弊机制是会误判的，应该提供一个专门的申诉渠道才更为合理。↵
↵
中国最有影响力的编程网站，洛谷，在申诉这件事情上就做得挺好。洛谷申诉的规则大致是以下条件满足其一：↵
↵
1. 申诉需要高水平选手，对应到 CF，可以是GM及以上选手代为申诉↵
2. 有全程录像↵
3. 其他一些，明显不是作弊的情况，比如出题人的一些失误操作↵
↵
虽然在申诉规则出来之时，大量的选手批判规则太不合理，有为难的成分，但是在实行许久之后，我并没有看到什么选手抱怨自己被误判了。↵
↵
所以我在想，CF 和 AT 为误判选手提供申诉渠道，是否具备一定的可行性呢？
