Turnstile

A turnstile, also called a baffle gate, is a form of gate which allows one person to pass at a time. It can also be made so as to enforce one-way traffic of people, and in addition, it can restrict passage only to people who insert a coin, a ticket, a pass, or similar. Thus a turnstile can be used in the case of paid access (sometimes called a faregate when used for this purpose), for example public transport as a ticket barrier or a pay toilet, or to restrict access to authorized people, for example in the lobby of an office building.

Turnstiles are used at a wide variety of settings, including stadiums, amusement parks, mass transit stations, office lobbies, airports, ski resorts, and casinos.

From a business/revenue standpoint, turnstiles give an accurate, verifiable count of attendance. From a security standpoint, they lead patrons to enter single-file, so security personnel have a clear view of each patron. This enables security to efficiently isolate potential trouble or to confiscate any prohibited materials. They can, on the other hand, become a serious safety issue when a speedy evacuation is needed.

Turnstile (disambiguation)

A turnstile is a pedestrian gate.

Turnstile may also refer to:

See also

Turnstile (symbol)

In mathematical logic and computer science the symbol has taken the name turnstile because of its resemblance to a typical turnstile if viewed from above. It is also referred to as tee and is often read as "yields", "proves", "satisfies" or "entails". The symbol was first used by Gottlob Frege in his 1879 book on logic, Begriffsschrift.

Martin-Löf analyzes the symbol thus: "...[T]he combination of Frege's Urteilsstrich, judgement stroke [ | ], and Inhaltsstrich, content stroke [—], came to be called the assertion sign." Frege's notation for a judgement of some content

can be then be read

In the same vein, a conditional assertion

can be read as:

In TeX, the turnstile symbol is obtained from the command \vdash. In Unicode, the turnstile symbol (⊢) is called right tack and is at code point U+22A2. On a typewriter, a turnstile can be composed from a vertical bar (|) and a dash (–). In LaTeX there is a turnstile package which issues this sign in many ways, and is capable of putting labels below or above it, in the correct places.