In mathematical logic and computer science the symbol \vdash has taken the name turnstile because of its resemblance to a typical turnstile if viewed from above. The symbol was first used by Gottlob Frege in his Begriffsschrift.The article on the Begriffsschrift describes its notation in detail.
This allows door 1 to be used as an exterior reader and door 2 as an internal reader. Door 1 lock relay activates on a valid swipe at door one's reader Door 2 lock relay activates on a valid swipe at door two's reader Close Glossary Window