The minimal uncountable well-ordered set

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In summary, the set of real numbers is a good example of a minimal uncountable well-ordered set where every section is countable. This example is helpful for those who are self-taught in Mathematics and need concrete examples to better understand the topic.
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topsquark
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I once asked about this on MHF and didn't really get anywhere with it. (I thought things made sense and eventually ended up just as confused as before.)

Does anyone have an example of the minimal uncountable well-ordered set, where every section is countable? I'm still at the point in my self taught Mathematical skills that I need examples in order to understand the topic. Sad, but true.

-Dan
 
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A good example of a minimal uncountable well-ordered set is the set of real numbers. This set is uncountable because it is infinitely large and it is well-ordered because every element can be compared to every other element and there is an overall ordering of the elements from smallest to largest. Moreover, the set is minimal because for any two elements in the set, there is no subset of the set that contains only those two elements.To see how this set has countable sections, we can consider the intervals between rational numbers. Since the rational numbers are countable, the set of real numbers can be divided into countably many distinct intervals. For example, the interval between 1/2 and 1 can be divided into the following countable sections: [1/2, 7/10), [7/10, 8/10), [8/10, 9/10), [9/10, 1]. This shows that every section of the set of real numbers is countable.
 

FAQ: The minimal uncountable well-ordered set

What is "The minimal uncountable well-ordered set"?

"The minimal uncountable well-ordered set" is a mathematical concept used to describe the smallest possible set that is uncountable and also well-ordered. It is also known as the first uncountable ordinal and is denoted by the symbol ω1.

How is this set different from the real numbers?

The minimal uncountable well-ordered set is a specific mathematical construct that is used to prove certain theorems in set theory and other areas of mathematics. While it shares some properties with the real numbers, such as being uncountable, it is not a subset of the real numbers and does not represent all possible real numbers.

What is the cardinality of this set?

The minimal uncountable well-ordered set has a cardinality of ℵ1, which is the smallest uncountable cardinal number. This means that it has a size that is larger than the set of natural numbers, but smaller than the set of real numbers.

How is this set related to Cantor's diagonal argument?

Cantor's diagonal argument is a proof that shows that there are different sizes of infinity, and that the real numbers are uncountable. This proof relies on the existence of the minimal uncountable well-ordered set, as it is used to construct a real number that is not included in any list of real numbers.

Why is this set important in mathematics?

The minimal uncountable well-ordered set is an important concept in mathematics because it provides a starting point for proving many theorems in set theory and other branches of mathematics. It also helps to illustrate the concept of different sizes of infinity and is a fundamental building block in the study of infinite sets.

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