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Name: Steve L.
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in set theory what does a line written above L U M U N
where L,M,N are sets and the U represents Union of these sets
the question appears like      L U M U N

I have searched high and low and found various solutions some saying that
is means NOT(L U M U N) and others saying that the line is a viniculum
which means it has no effect can you help please?


It can vary from text to text, or even person to person. I can only tell you what it means to me. When I put a bar above a set label, I mean everything NOT in the set.

If you have no way to find out before answering the question, one option is to answer it both ways. Another is to look at context. Are there any other questions with set references? If ALL set references have such a bar, use it as a verniculum. If only some have a bar, use it to mean NOT.

Dr. Ken Mellendorf

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