In dictionaries:
optional feature
Available but not always included.
optional hyphen
optional referendum
The optional referendum is a referendum which comes from a request by governmental authorities or the public.
clothing optional
Optional attire at designated places.
optional stopping
optional dividend
Dividend paid at company's discretion.
optional payment bond
Bond allowing voluntary additional payments.
Optional Practical Training
In the United States, Optional Practical Training is a period during which undergraduate and graduate students with F-1 status who have completed or have been pursuing their degrees for one academic year are permitted by the United States Citizenship and Immigration Services to work for one year on a student visa towards getting practical training to complement their education.
Optional stopping theorem
In probability theory, the optional stopping theorem (or sometimes Doob's optional sampling theorem, for American probabilist Joseph Doob) says that, under certain conditions, the expected value of a martingale at a stopping time is equal to its initial expected value.
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