Operation

Operation or Operations may refer to:

Military operation

A military operation is the coordinated military actions of a state, or a non-state actor, in response to a developing situation. These actions are designed as a military plan to resolve the situation in the state's favor. Operations may be of a combat or non-combat nature and are referred to by a code name for the purpose of national security. Military operations are often known for their more generally accepted common usage names than their actual operational objectives.

Types of military operations

Military operations can be classified by the scale and scope of force employment, and their impact on the wider conflict. The scope of military operations can be:

Set theory (music)

Musical set theory provides concepts for categorizing musical objects and describing their relationships. Many of the notions were first elaborated by Howard Hanson (1960) in connection with tonal music, and then mostly developed in connection with atonal music by theorists such as Allen Forte (1973), drawing on the work in twelve-tone theory of Milton Babbitt. The concepts of set theory are very general and can be applied to tonal and atonal styles in any equally tempered tuning system, and to some extent more generally than that.

One branch of musical set theory deals with collections (sets and permutations) of pitches and pitch classes (pitch-class set theory), which may be ordered or unordered, and can be related by musical operations such as transposition, inversion, and complementation. The methods of musical set theory are sometimes applied to the analysis of rhythm as well.

Mathematical set theory versus musical set theory

Although musical set theory is often thought to involve the application of mathematical set theory to music, there are numerous differences between the methods and terminology of the two. For example, musicians use the terms transposition and inversion where mathematicians would use translation and reflection. Furthermore, where musical set theory refers to ordered sets, mathematics would normally refer to tuples or sequences (though mathematics does speak of ordered sets, and although these can be seen to include the musical kind in some sense, they are far more involved).

Operation (game)

Operation is a battery-operated game of physical skill that tests players' hand-eye coordination and fine motor skills. The game's prototype was invented in 1964 by John Spinello, a University of Illinois industrial design student at the time, who sold his rights to the game to Milton Bradley for a sum of USD $500. Initially produced by Milton Bradley in 1965, Operation is currently made by Hasbro, with an estimated franchise worth of USD $40 million.

The game is a variant on the old-fashioned electrified wire loop game popular at funfairs around the United States. It consists of an "operating table", lithographed with a comic likeness of a patient (nicknamed "Cavity Sam") with a large red lightbulb for his nose. In the surface are a number of openings, which reveal cavities filled with fictional and humorously named ailments made of plastic. The general gameplay requires players to remove these plastic ailments with a pair of tweezers without touching the edge of the cavity opening.

Operation (mathematics)

In mathematics, an operation is a calculation from zero or more input values (called "operands") to an output value.

(Operations, as defined here, should not be confused with operators on vector spaces nor arithmetic operations on numbers.)

Types of operation

There are two common types of operations: unary and binary. Unary operations involve only one value, such as negation and trigonometric functions. Binary operations, on the other hand, take two values, and include addition, subtraction, multiplication, division, and exponentiation.

Operations can involve mathematical objects other than numbers. The logical values true and false can be combined using logic operations, such as and, or, and not. Vectors can be added and subtracted. Rotations can be combined using the function composition operation, performing the first rotation and then the second. Operations on sets include the binary operations union and intersection and the unary operation of complementation. Operations on functions include composition and convolution.

Invasion of Yugoslavia

The invasion of Yugoslavia, also known as the April War (Slovene: Aprilska vojna, Serbian: Aprilski rat,Croatian: Travanjski rat) or Operation 25, was a German-led attack on the Kingdom of Yugoslavia by the Axis powers which began on 6 April 1941 during World War II. The order for the invasion was put forward in "Führer Directive No. 25", which Adolf Hitler issued on 27 March 1941, following the Yugoslav coup d'état.

The invasion commenced with an overwhelming air attack on Belgrade and facilities of the Royal Yugoslav Air Force (VVKJ) by the Luftwaffe (German Air Force) and attacks by German land forces from southwestern Bulgaria. These attacks were followed by German thrusts from Romania, Hungary and the Ostmark. Italian forces were limited to air and artillery attacks until 11 April, when the Italian army attacked towards Ljubljana (in modern-day Slovenia) and through Istria and Lika and down the Dalmatian coast. On the same day, Hungarian forces entered Yugoslav Bačka and Baranya, but like the Italians they faced practically no resistance. A Yugoslav attack into the northern parts of the Italian protectorate of Albania met with initial success, but was inconsequential due to the collapse of the rest of the Yugoslav forces.