TLA+ leaves the truth value of formulas such as 1 = "a" or 1 = {} unspecified, and therefore we cannot know if, say,"a" \in {1, "b"}holds or not. This explains the error message that TLC produces.StephanOn 7 Feb 2020, at 11:45, Leroy van Engelen wrote:Hi,It seems that TLC does not support sets of mixed 'types': evaluating {1, "a"},  {1, {}}, "a" \in {1} result in errors like "Attempted to compare string "a" with non-string".I thought sets would allow any mixed types of elements. Or is this a TLC optimization. I am trying to use to improve on the Json module to support arbitrary inputs, not just sequences.Regards,-Leroy van Engelen -- You received this message because you are subscribed to the Google Groups "tlaplus" group. To unsubscribe from this group and stop receiving emails from it, send an email to tlaplus+unsubscribe@xxxxxxxxxxxxxxxx. To view this discussion on the web visit https://groups.google.com/d/msgid/tlaplus/1fb74ada-56d2-486e-8476-0c097236ed1b%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "tlaplus" group. To unsubscribe from this group and stop receiving emails from it, send an email to tlaplus+unsubscribe@xxxxxxxxxxxxxxxx. To view this discussion on the web visit https://groups.google.com/d/msgid/tlaplus/44482723-759A-4AA0-B3B8-3BC97828C61D%40gmail.com.