Sets, the origin

VIEW:411 DATA:2020-03-20

The human mind is finite, so we cannot see everything at the same time. For this we use a rule, which is the sets. Together is when we separate objects or ideas, so that we can understand the parts. Since we cannot really know the whole. The use of sets makes it easier to understand the parts so that you can change the parts and see what happens in the whole. It may seem strange, but let's use an example. Imagine that on my social media I have 5000 followers, and I want to post a message, but first I want to post to my closest friends, to see what they think. So, my first set is from the closest friends. With that I see that my closest friends liked the message, then I publish it for the 5000 followers, and I see that many people liked it, and so now I publish it for anyone to see.

What happened? First, I auditioned with my best friends, so I was able to understand that they liked it, which makes me expand the set. See that the act of understanding the sets can be very useful. So, it is good to understand how to write or represent such things to use the best of this tool.

Imagine that A is the set of all my best friends. So, let's say that the individual "x" is a great friend of mine, so he belongs to my best friends. Thus, we write as represented.

But the "y" individual is just a person I saw on social media, and we didn't even talk. So "y" does not belong to the group of my best friends, as shown in the representation.

If you make drawings, it usually becomes difficult and laborious. Thus, we can represent as lists.

Then, we can see the list of best friends, and friends, who are not part of set A.

The practice is to be able to define specific groups. For example, define the following set in A.

If we look at it, set A is made up of whole, even and non-negative numbers.

And set B? Could we say what about him?

We can say that such a set represents Arabic numbers, because Arabic numbers are ten numbers, composed from zero to 9. But we can also say that the set is made up of non-negative integers less than or equal to 9.

Note that defining a set involves knowledge about that set. Like the person who knows his best friends, he knows who is not in this set. So knowledge in general is very important.