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Q: Is it possible for a finite set to have the same cardinality as its power set?

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Two sets are equivalent if they have the same cardinality. For finite sets this means that they must have the same number of distinct elements. For infinite sets, equal cardinality means that there must be a one-to-one mapping from one set to the other. This can lead to some counter-intuitive results. For example, the cardinality of the set of integers is the same as the cardinality of the set of even integers although the second set is a proper subset of the first. The relevant mapping is x -> 2x.

The cardinality of finite sets are the number of elements included in them however, union of infinite sets can be different as it includes the matching of two different sets one by one and finding a solution by matching the same amount of elements in those sets.

The cardinality of [0,1) is equal to the cardinality of (0,1) which has the same cardinality as the real numbers.

Actually, infinity is not a natural number. It is simply a concept of having no upper bound. However, it is possible to have and compare different infinities. For example, we use aleph_0 to represent the cardinality (size) of the set of natural numbers. The cardinality of the set of integers, rational numbers, gaussian integers all have the same cardinality of aleph_0. The set of real numbers has cardinality aleph_1, which is greater than aleph_0. It is possible to create a sequence of increasing infinities (aleph_2, aleph_3, ...), which are called transfinite numbers.

In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table.The lower the cardinality, the more duplicated elements in a column. Thus, a column with the lowest possible cardinality would have the same value for every row. SQL databases use cardinality to help determine the optimal query plan for a given query.

Equivalent sets are sets that have the same cardinality. For finite sets it means that they have the same number of distinct elements.For infinite sets, though, things get a bit complicated. Then it is possible for a set to be equivalent to a proper subset of itself: for example, the set of all integers is equivalent to the set of all even integers. What is required is a one-to-one mapping, f(x) = 2x, from the first set to the second.

Infinity squared is infinity. But there's more to it.Mathematicians describe different kinds of infinities:The cardinality(number) of natural numbers is called Aleph0 () . This is infinite, and it has some peculiar properties:The cardinality of even numbers is also Aleph0.As is the cardinality of odd numbers.As is the cardinality of rational numbers (which you could view as infinity squared, but it still gives you infinity.The cardinality of countable ordinal numbers is called Aleph1 ().The cardinality of the real numbers is two to the exponent of Aleph0 ( ). The continuum hypothesis says this is equal to Aleph1.Basically, if you square an infinite set from a given cardinality, the cardinality stays the same (meaning Aleph0 squared is still Aleph0, etc.)If your mind just burst(cause mine did! 0_o), do not worry. This is a common reaction to set theory.See the related link for more on Aleph numbers, which are how mathematicians view infinity.

No. The "smallest" infinity is the cardinality of the natural numbers, N. This cardinality is named Aleph-null. Rational numbers also have the same cardinality as do n-tuples of rational numbers. The next larger cardinality is that of the real numbers. This is the "continuum, C, which equals 2aleph-null. As with the cardinality of the natural numbers, n-tuples of reals have the same cardinality. The point about introducing n-tuples, is that they are used to denote points in n-dimensional space. If you want more read some of the Wikipedia articles of Cantor, Hilbert's Grand Hotel. These could lead you to many more related articles - though sadly, not infinitely many!

The order of a group is the same as its cardinality - i.e. the number of elements the set contains. The order of a particular element is the order of the (cyclic) group generated by that element - i.e. the order of the group {...a-4, a-3, a-2, a-1, e, a, a2, a3, a4...}. If these powers do not go on forever, it will have a finite order; otherwise the order will be infinite.

The order of a group is the same as its cardinality - i.e. the number of elements the set contains. The order of a particular element is the order of the (cyclic) group generated by that element - i.e. the order of the group {...a-4, a-3, a-2, a-1, e, a, a2, a3, a4...}. If these powers do not go on forever, it will have a finite order; otherwise the order will be infinite.

There are more irrational numbers than rational numbers. The rationals are countably infinite; the irrationals are uncountably infinite. Uncountably infinite means that the set of irrational numbers has a cardinality known as the "cardinality of the continuum," which is strictly greater than the cardinality of the set of natural numbers which is countably infinite. The set of rational numbers has the same cardinality as the set of natural numbers, so there are more irrationals than rationals.

yes, it is possible. in fact in power systems all the generators do not run with same power factor.

There is no one to one correspondence between the real numbers and the set of integers. In fact, the cardinality of the real numbers is the same as the cardinality of the power set of the set of integers, that is, the set of all subsets of the set of integers.

This is NOT true.The cardinality of the set of points in a circle is the same as the cardinality of the set of points in a line.First, break the circle and straighten it out. I think you would agree that the number of points remains the same.Now apply some continuous monotonic function that takes one end of that line segment and assigns it to -infinity and the other end to +infinity. I think you would agree that this is possible.We have now made a one-to-one, invertible correspondence between the points in the original circle and the points in a line, demonstrating that the two objects have the same cardinality.Roughly speaking!

No. The number of subsets of that set is strictly greater than the cardinality of that set, by Cantor's theorem. Moreover, it's consistent with ZFC that there are two sets which have different cardinality, yet have the same number of subsets.

Infinity is not just really big number - and consequently the concepts of rational vs irrational cannot be applied to it. It is a marvelously useful concept with great utility in mathematics but don't confuse it for being the same as a number that we could write out and categorize just because we have a symbol for representing it. When you stick infinity into an equation you get things like "limits" rather than a fixed answer; for example - for the function f(x) = (x-1)/x, if x = ∞ you don't actually get a value for the function- rather you get a limit that it approaches as x goes off to infinity; in this case the limit as x approaches infinity is 1. For the function f(x) = (x-2)/x, the limit as x approaches infinity is ALSO 1, and for the function f(x) = x/(x-1) the limit as x approaches infinity is .... 1. Obviously for any finite number they will not have the same value, but conceptually they all converge to the same value as you go to infinity. Hopefully this illustrates why you cannot apply the concept of rational vs irrational to "infinity".

Curiously, both sets are countably infinite and so their cardinality is the same.

There are not more tens. The cardinality ("count") of the set of tens is exactly the same as the cardinality of the set of hundreds. The mapping f(x) = 10x where x is a multiple of 10 is bijective. Consequently, its domain and range are of the same "size". The words "count" and "size" are in quotation marks because the relevant values are infinite.

They are both infinite sets: they have countably infinite members and so have the same cardinality - Aleph-null.

A countable set is defined as one whose elements can be put into one-to-one correspondence with elements of the set of counting numbers or some subset of it. A countable set can be infinite: for example all even numbers. This raises the strange concept where a subset (positive even numbers) has the same cardinality as all counting numbers - which should be a set that is twice as large! Even more confusingly (perhaps) is the fact that the set of all rational numbers also has the same cardinality as the set of counting numbers. You need to go to the set of irrationals or bigger before you get to uncountable sets. So you have the weird situation in which there are more irrationals between 0 and 1 than there are rationals between from 0 and infinity (if infinity can be treated as a value)! There is a minority definition of countable which means containing a finite number of elements as opposed to uncountable meaning infinitely many elements. However, these definitions are essentially the same as the finite sets and infinite sets and so there is little point in using them.

The source is finite. Any real world power source is finite. You will see the same thing with a battery, for example (the battery has internal resistance). If you have no voltage at that recepticle, the resistance should approach infinite due to an open circuit (open breaker, fuse, broken conductor, etc.).

Nobody knows for certain, but most theories predict the universe is finite but unbounded, the same way the surface of a sphere is finite but doesn't have any edges.

For finite sets similarity simply requires both sets to have the same number of distinct elements (the same cardinality). For example, {1,2,3} and {a,b,c,a}. The second set appears to have 4 elements but, in fact, it has only three distinct elements - the same as the first. Similarity of sets does get more complicated (and counter-intuitive) when dealing with infinite sets. It is probably not too hard to see that the set of odd integers (infinitely many) is similar to the set of even integers (infinitely many). But it is not so easy to see that the set of odd integers is similar to the set of ALL integers. This is because you can define a mapping from the odd integers to all integers as: 2n-1 to n Proving that this mapping is bijective (injective and surjective) shows that the two sets have the same cardinality.

A Natural infinite set refers to one whose members can be put into 1-to-1 correspondence with the natural numbers, while a real infinite set is one whose members can be put into 1-to-1 correspondence with the real numbers. Although both sets are infinite, they are not of the same cardinality (size).The cardinality of the natural infinite set is denoted by Ã€0 or Aleph-null. The cardinality of the real infinite set is 2 to the power Ã€0, which is denoted by C. (Actually Aleph looks like an N with wriggly lines but this browser is incapable of displaying it.)For more on the cardinality of infinite sets, see the related links. Georg Cantor's diagonal argument is exquisite - simple but immensely powerful. If you want to get a feel for transfinite arithmetic - read about Hilbert's Hotel paradox.

Two line segments of the same finite size.