Where does variety collide?

In cybernetics, the variety of a system is the number of distinct states it can take, and Ashby's law of requisite variety holds that a regulator can keep a system stable only if it commands at least as much variety as the disturbances acting on it, summed up as "only variety can absorb variety". W. Ross Ashby set this out in his 1956 An Introduction to Cybernetics, where variety is counted as the number of distinguishable elements or states. The referent is a countable measure of how many states a system or controller can occupy, a formal quantity in control theory, not a shopper's taste for change, a form of a language, or a rank of plant.[1]

Unit

The number of distinct states a system can take, often given as its base-two logarithm in bits

Recovery means

Not applicable

Measured by

Counted as the number of distinguishable states, and compared between the disturbance set and the controller's response set

In linguistics, a variety is any distinct form of a language marked off by its speakers or its uses, such as a regional dialect, a social dialect, or a register tied to a situation, treated as a neutral term that avoids ranking one form above another. Hudson's 1996 Sociolinguistics defined a variety as a set of linguistic items with a similar social distribution, so a dialect, an accent, and a specialised register all count as varieties. The referent is a describable form of human language, identified by the features its speakers share, not a measure of a system's states, a shopper's switching, or a category of crop.[2]

Unit

One recognisable form of a language, defined by the linguistic features its speakers share

Recovery means

Not applicable

Measured by

Described by collecting the pronunciations, words, and structures that pattern together across a group or a setting

In botany, a variety (Latin varietas) is a taxonomic rank below species, used for a group of plants within a species that differs in a minor but heritable way, such as flower colour or growth form, while still interbreeding freely with the rest of the species. Hamilton and Reichard's 1992 review of the use of subspecies, variety, and forma in classifying wild plants examined how botanists apply this rank in practice. The referent is a rank in biological classification, a named group of plants, not a count of a system's states, a shopper's switching, or a form of a language. It is also distinct from a cultivar, a variety selected and maintained under cultivation.[3]

Unit

A named group of plants ranked below a species

Recovery means

Not applicable

Measured by

Assigned by describing the heritable features that set the group apart and publishing the name under the botanical code