子集、幂集和通用集
为了正确理解事物并长时间记住它们,人类更喜欢将信息保存在一堆或类别中,将相同类型的信息归为一个类别,这样信息看起来更整洁,更容易记住。集合也以相同的方式定义。为了保持属于同一类别的元素,它们被保存在一个集合中,这样在数学上也可以整齐地排列数据。但是,集合不允许提及元素的质量。例如,可以将 8 班的所有女孩都放在一个集合中,但不能将 8 班的所有漂亮女孩都视为集合的示例。让我们更详细地了解集合。
套
集合被定义为定义明确的数据集合。集合中存在的数据称为元素,属于一个集合的每个元素彼此不同,但它们所属的类别始终相同,例如,一袋不同类型的水果,全自然数,等等。
Examples of Sets:
- {1, 2, 3, 4, 5} ⇢ Example of Finite set.
- {} ⇢ Example of Null Set.
- {a: a is an odd number} ⇢ Example of Infinite set.
- {p} ⇢ Example of singleton set.
子集
如果一个集合的所有元素都属于其他集合,则该集合将被称为另一个集合的子集。子集表示为“ ⊆”。如果集合 A 是集合 B 的子集,则表示为 A⊆ B。
Example of a Subset,
Set A= {m, n, o, p, q}
Set B= {k, l, m, n, o, p, q, r}
Then, A ⊆ B
适当的设置
如果集合 A 的所有元素都存在于集合 B 中,并且集合 B 的元素数量更多,则集合 A 是集合 B 的真集。真集表示为 ' ⊂'
具有相同数量元素的两个集合永远不可能是彼此的真集,因此,一个集合永远不是自身的真集。
Note: All Proper sets are Subsets, but all Subsets can not be considered as Proper sets.
电源组
幂集定义为给定集合的所有可能子集的集合。这个定义看起来有点混乱,但实际上,幂集很容易理解。想象一个包含一些元素的集合,现在写出可以为特定集合编写的所有可能的子集,将子集视为元素,将它们放在单独的集合中,获得的这个集合将被称为幂集。
电源集的示例,
设置 A = {2,3}
A = {}、{2}、{3}、{2、3} 的可能子集
A 的幂集 = P(A)= {{}, {2}, {3}, {2, 3}}
Note: If there are ‘n’ number of elements, then the number of elements present in the Power set will be 2n.
通用套装
通用集是所有集合的主人,也就是说,它包含所有给定集合中存在的所有元素。全集用U表示,在维恩图中表示为一个矩形,其他所有集合都画在矩形内,这样做是为了表明全集包含所有可能的元素。
假设集合 A 和集合 B 是全集的一部分,
设置 A = {1, 2, 3, 4}
设置 B= {2, 4, 5, 6}
U= {1, 2, 3, 4, 5, 6}
这应该在维恩图上看起来像这样,
示例问题
问题1:说明以下陈述是对还是错,
- 每个集合都是它自己的一个子集
- 如果集合 A 的所有元素都存在于集合 B 中,则集合 B 成为集合 A 的子集。
- Universal 绝不是任何其他集合的子集。
- 并非所有集合都是通用集合的子集。
- 幂集不包括空集。
回答:
- True. Every set can be denoted as a subset of itself.
- False. The true statement should be that set A ⊂ set B.
- True. Universal set contains all the elements in itself.
- False. All the sets are subsets of U.
- False. A Power set includes empty set.
问题 2:解释以下哪些集合是集合 P 的子集,
设置 P = {1, 3, 5, 7, 9, 11, 13, 15,17,19}
- 设置 A = {a, 1, 0, 2}
- 设置 B ={3, 7, 9}
- 设置 C = {1, 4, 6, 11}
- 设置 D = {19,1}
- 设置 E ={9, 13, 15, 17}
回答:
- Set A has elements a, 1, 0, 2 which are not present in the Set P. Therefore, set A is not a Subset.
- Set B has elements which are present in set P, Therefore, Set B ⊆ Set P
- Set C has 2 extra elements. Hence, not a subset of P
- Set D has 1, 19 as element. Therefore, Set D ⊆ Set P
- Set E has all its elements matching the elements of set P. Hence, Set E ⊆ Set P.
问题3:什么类型的元素不能放在Set中?
回答:
Anything that talks about quality or characteristic of the elements, like the good, the bad, can not be put in a set. For example, “all the good football players “This statement can not be put in a set, Or” all the students who performed poor in the class” can not be put in a set.
问题 4:子集和真集有什么区别?
回答:
If a set A has all its elements present in set B, then it can be said that set A ⊆ set B, one important thing to notice is that both sets can be equal and still be subsets of each other.
If set A has all its elements present in set B and the elements in set B are more than the elements in set A, then it can be said that set A is a proper set of set B. It is represented as A ⊂ B.
问题 5:集合 P= {a, b, c} 的幂集是多少?
回答:
There are 3 elements in the set P, therefore, it will have 23 elements present in its Powerset. It can also be said that there are 8 subsets possible for set P.
Subsets of P= {}, {a}, {b}, {c}, {a, b}, {b, c}, {a, c}, {a, b, c}.
Power set of P= {{}, {a}, {b}, {c}, {a, b}, {a, c}, {b, c}, {a, b, c}}.
问题 6:用维恩图表示下面给出的信息,
U= {1, 3, 5, 6, 7, 9,11, 13, 15}
设置 A= {1, 3,5}
设置 B= {5, 7, 9}
回答:
The sets A and B have all its elements present in U, hence, U is clearly the universal set of set A and B.
Set A and set B has 5 as a common element between the, based on this information, Venn diagram can be easily drawn