where, and are nonterminal symbols, α is a terminal symbol ( a symbol that represents a constant value ), is the start symbol, and ε is the empty string.

where, and are nonterminal symbols, and α is a terminal symbol.

In the following descriptions, α, β, and γ represent any string of terminals / nonterminals ( including the empty string ), X and Y represent single nonterminals, and a represents a terminal symbol.

* Scanning: If a is the next symbol in the input stream, for every state in S ( k ) of the form ( X → α • a β, j ), add ( X → α a • β, j ) to S ( k + 1 ).

Right ascension ( abbreviated RA ; symbol α ) is the astronomical term for one of the two direction coordinates of a point on the celestial sphere in the equatorial coordinate system, usually combined with declination.

where A is a nonterminal symbol, α is a terminal symbol,

FOLLOW ( I ) of an Item I → α • B β, x is the set of terminals that can appear after nonterminal B, where α, β are arbitrary symbol strings, and x is an arbitrary lookahead terminal.

The significance level is usually denoted by the Greek symbol α ( lowercase alpha ).

* α, the conventional symbol for angular eccentricity

* α, a symbol for navigational azimuth

* α, a symbol for one of the Feigenbaum constants describing a bifurcation diagram, in mathematics

* α, a symbol representing the probability of a type I error in statistics

* α, a symbol for the angle of attack in aerodynamics

* α, a symbol for angular acceleration in physics

* α, a symbol for coefficient of thermal expansion in thermodynamics

* α, a symbol for thermal diffusivity in thermodynamics

* α, a symbol for common-base current gain of a transistor in electronics

where α and β are arbitrary scaling constants and represents the tensor product ( which is not related to the vector cross product, despite their similar symbol ).

Untriseptium, element 137, is sometimes called feynmanium ( symbol Fy ) because Richard Feynman noted that a simplistic interpretation of the relativistic Dirac equation runs into problems with electron orbitals at Z > 1 / α = 137, suggesting that neutral atoms cannot exist beyond untriseptium, and that a periodic table of elements based on electron orbitals therefore breaks down at this point.

Arcturus is notable for its high proper motion, larger than any first magnitude star in the stellar neighborhood other than α Centauri.

for an arbitrary real or complex number α ( the order of the Bessel function ); the most common and important cases are for α an integer or half-integer.

Although α and − α produce the same differential equation, it is conventional to define different Bessel functions for these two orders ( e. g., so that the Bessel functions are mostly smooth functions of α ).

Bessel functions of the first kind, denoted as J < sub > α </ sub >( x ), are solutions of Bessel's differential equation that are finite at the origin ( x = 0 ) for integer α, and diverge as x approaches zero for negative non-integer α.

Plot of Bessel function of the first kind, J < sub > α </ sub >( x ), for integer orders α = 0, 1, 2.

On the other hand, for integer order α, the following relationship is valid ( note that the Gamma function becomes infinite for negative integer arguments ):

Plot of Bessel function of the second kind, Y < sub > α </ sub >( x ), for integer orders α = 0, 1, 2.

When α is an integer, moreover, as was similarly the case for the functions of the first kind, the following relationship is valid:

For integer order α = n, J < sub > n </ sub > is often defined via a Laurent series for a generating function:

This orthogonality relation can then be used to extract the coefficients in the Fourier – Bessel series, where a function is expanded in the basis of the functions J < sub > α </ sub >( x u < sub > α, m </ sub >) for fixed α and varying m.

where α is the fine-structure constant and j is a number which is the total angular momentum eigenvalue ; that is, depending on the direction of the electron spin.

There are many physical constants in science, some of the most widely recognized being the speed of light in vacuum c, the gravitational constant G, Planck's constant h, the electric constant ε < sub > 0 </ sub >, and the elementary charge e. Physical constants can take many dimensional forms: the speed of light signifies a maximum speed limit of the Universe and is expressed dimensionally as length divided by time ; while the fine-structure constant α, which characterizes the strength of the electromagnetic interaction, is dimensionless.

The fine-structure constant α is probably the best known dimensionless fundamental physical constant.

In physics, the fine-structure constant ( usually denoted α, the small Greek letter alpha ) is a fundamental physical constant, namely the coupling constant characterizing the strength of the electromagnetic interaction.

The theory of QED predicts a relationship between the dimensionless magnetic moment of the electron and the fine-structure constant α ( the magnetic moment of the electron is also referred to as " Landé g-factor " and symbolized as g ).

The fine-structure constant α has several physical interpretations.

The first physical interpretation of the fine-structure constant α was as the ratio of the velocity of the electron in the first circular orbit of the relativistic Bohr atom to the speed of light in the vacuum.

Shlyakhter is a Russian physicist who noted that the existence of the natural nuclear fission reactor at Oklo in Gabon gave evidence that the physical fine-structure constant α has changed less than 10 < sup >− 17 </ sup > per year over the last two billion years.

* Physics: α =, the fine-structure constant.

Fred Adams has done a similar study to Stenger, investigating the structure of stars in universes with different values of the gravitational constant G, the fine-structure constant α, and a nuclear reaction rate parameter C. His study suggests that roughly 25 % of this parameter space allows stars to exist.

The scale of the fine structure splitting relative to the gross structure splitting is on the order of ( Zα )< sup > 2 </ sup >, where Z is the atomic number and α is the fine-structure constant, a dimensionless number equal to approximately.

where is the reduced Planck's constant and α is the fine-structure constant ( a relativistic correction for the Bohr model ).