domain

中文： 领域、区域、域名、域

1. A geographic area owned or controlled by a single person or organization. · The king ruled his domain harshly.
2. A field or sphere of activity, influence or expertise. · Dealing with complaints isn't really my domain: get in touch with customer services.· His domain is English history.
3. A group of related items, topics, or subjects.
4. The set of input (argument) values for which a function is defined.
5. The set A; The subset of A consisting of elements a of A such that there exists an element b in B with (a,b) in R.
6. A ring with no zero divisors; that is, in which no product of nonzero elements is zero.
7. An open and connected set in some topology. For example, the interval (0,1) as a subset of the real numbers.
8. Any DNS domain name, particularly one which has been delegated and has become representative of the delegated domain name and its subdomains.

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