8.1. Of the three boys named Anton, Vanya, and Sasha, only one always tells the truth. Anton said: "Vanya does not always tell the truth," Vanya said: "I do not always tell the truth," and Sasha said: "Anton does not always tell the truth." Who among them always tells the truth, given that at least one of them lied?

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# Solution

1) It is easy to see that Vanya is telling the truth (if we assume that he is lying and the statement "I do not always tell the truth" is not true, then the truth would be: "I always tell the truth," which would lead to a contradiction).
2) Since Anton's statement has the same meaning, Anton is also telling the truth.
3) According to the condition, one of the boys lied, so it must be Sasha.
4) Sasha said: "Anton does not always tell the truth" - and he lied, which means Anton always tells the truth.

Answer: Anton.