Browse Definitions :
Definition

cardinality

See also integer, natural number, rational number, and real number.

The term cardinality refers to the number of cardinal (basic) members in a set. Cardinality can be finite (a non-negative integer) or infinite. For example, the cardinality of the set of people in the United States is approximately 270,000,000; the cardinality of the set of integers is denumerably infinite.

In tables, the number of rows (or tuples) is called the cardinality. In practice, tables always have positive-integer cardinality. The reason for this is simple: tables with no rows, or with a negative number of rows, cannot exist. In theory, however, tables with denumerably infinite cardinality can exist. An example is a multiplication table of non-negative integers in which entries are implied for all possible values:

0 1 2 3 ..
1 1 2 3 ..
2 2 4 6 ..
3 3 6 9 ..
: : : :

The concept of cardinality is of interest to set theoreticians because it has been used to demonstrate that some infinite sets are larger than others. The cardinality of the set of real numbers is greater than the cardinality of the set of integers, even though both sets are infinite. The cardinality of the set of integers is called aleph-null or aleph-nought; the cardinality of the set of real numbers is called aleph-one.

One of the great mysteries of mathematics is contained in the question, "What is the cardinality of the set of points on a geometric line?" Generally it is presumed to be aleph-one; the set of points on a line is thought to correspond one-to-one with the set of real numbers. This is by no means a trivial supposition, and has become known as the Continuum Hypothesis.

This was last updated in September 2005
SearchCompliance
  • compliance risk

    Compliance risk is an organization's potential exposure to legal penalties, financial forfeiture and material loss, resulting ...

  • information governance

    Information governance is a holistic approach to managing corporate information by implementing processes, roles, controls and ...

  • enterprise document management (EDM)

    Enterprise document management (EDM) is a strategy for overseeing an organization's paper and electronic documents so they can be...

SearchSecurity
  • computer forensics (cyber forensics)

    Computer forensics is the application of investigation and analysis techniques to gather and preserve evidence from a particular ...

  • multifactor authentication (MFA)

    Multifactor authentication (MFA) is a security technology that requires more than one method of authentication from independent ...

  • insider threat

    An insider threat is a category of risk posed by those who have access to an organization's physical or digital assets.

SearchHealthIT
SearchDisasterRecovery
  • risk mitigation

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

SearchStorage
  • cloud storage

    Cloud storage is a service model in which data is transmitted and stored on remote storage systems, where it is maintained, ...

  • cloud testing

    Cloud testing is the process of using the cloud computing resources of a third-party service provider to test software ...

  • storage virtualization

    Storage virtualization is the pooling of physical storage from multiple storage devices into what appears to be a single storage ...

Close