F91 may refer to :
*
F91 Dudelange
F91 Dudelange (; , ) is a Luxembourgish professional Association football, football club based in Dudelange which plays in the Luxembourg National Division.
It was formed in 1991 as a merger between three teams in the town: Alliance Dudelange, ...
, a football club, based in Dudelange in southern Luxembourg
* ''
Mobile Suit Gundam F91
is a 1991 anime film. It was ''Gundam'' creator Yoshiyuki Tomino's attempt to launch a new ''Gundam'' saga, set 30 years after '' Char's Counterattack''. He re-teamed with character designer Yoshikazu Yasuhiko and mecha designer Kunio Okawara for ...
'', a 1991 animated film
*
HMS Brazen (F91)
HMS ''Brazen'' was a Type 22 frigate of the Royal Navy. She was completed three months ahead of schedule due to the Falklands War.
Royal Navy service
''Brazen'' served on the Armilla Patrol which became a task force during the Gulf War as par ...
, a 1981 British Royal Navy Type 22 frigate
*
HMS Murray (F91)
HMS ''Murray'' (F91) was one of a dozen Blackwood-class frigate (also known as the Type 14 class) of second-rate anti-submarine frigates built for the Royal Navy in the 1950s. She was named for George Murray, who served during the late 18th ...
, a British Royal Navy Blackwood class second-rate anti-submarine frigate
* Republic
XF-91 Thunderceptor
The Republic XF-91 Thunderceptor (originally designated XP-91) is a mixed-propulsion prototype interceptor aircraft, developed by Republic Aviation. The aircraft would use a jet engine for most flight, and a cluster of four small rocket engines ...
, a rocket-jet hybrid interceptor
*
Casio F-91W
The Casio F-91W is a digital watch manufactured by Japanese electronics company Casio. Introduced in June 1989 as a successor of the F-87W, it is popular for its low price, long battery life and iconic design. As of 2011, annual production of the ...
, a common and inexpensive digital watch, claimed by some to be associated with
terrorism
Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war aga ...
* The
McCarthy 91 function
The McCarthy 91 function is a recursive function, defined by the computer scientist John McCarthy as a test case for formal verification within computer science.
The McCarthy 91 function is defined as
:M(n)=\begin
n - 10, & \mboxn > 100\mbox \ ...
, a recursively defined mathematical function
and also:
*
Conduct disorders ICD-10 code
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