1. ## Re: Positive sets

Since "positive sets" is not a standard term, we are unable to give you the definition. I made my guess about its meaning in post #13.

Most likely, to solve these problems you need various laws about set operations, like distributivity of intersection over union and vice versa and De Morgan's laws, as well as the inclusion–exclusion principle.

2. ## Re: Positive sets

Originally Posted by ehpoc
I missed the class where he introduced positive sets. I started this thread so someone could confirm what exactly is meant by positive sets so I could educate myself on them.
The first thing I'd do is look online to see if the definition is a common one (and quickly discover it is not).

The second thing I'd do is check your book's index and look through class notes.

The third thing I'd do, if you don't have a friend in the class, is ask the professor by email: "Can you define positive set? I missed that class, and can't find the definition in the book or online."

This is really something you should jump on quickly, as soon as you realize you don't have what you need to complete an assignment.

(Also, I finally realize why I didn't gather what "+" was supposed to stand for...the other poster didn't put up the cardinality notation, so "+" was addition on natural numbers, not a set operation. Derp.)

3. ## Re: Positive sets

the definition given in class is "Given set "A,B,C,...." A positive set is the intersection of any sub-collection of A, B, C, ... without using complements or universal set"

good luck

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