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A vertical stroke with a bar to its right, meaning 'proves'.
Also known as: Proves sign, Yields, Assertion sign
The turnstile separates assumptions from what can be derived from them inside a formal system. It is a claim about derivation rather than about truth, which is exactly what distinguishes it from the double turnstile that a reader will meet on the same page.
Says that the formula on the right can be derived from the assumptions on the left within a stated formal system.
Contexts: Mathematics
Is a syntactic claim about proof rather than a semantic claim about truth, which is the distinction it exists to mark.
Contexts: Mathematics
An upright stroke of full height with a shorter horizontal line joining its middle and extending to the right.
One means derivable, the other means true in every model.