Look up Λ or λ in Wiktionary, the free dictionary.

Greek alphabet
Αα Alpha Νν Nu Ββ Beta Ξξ Xi Γγ Gamma Οο Omicron Δδ Delta Ππ Pi Εε Epsilon Ρρ Rho Ζζ Zeta Σσς Sigma Ηη Eta Ττ Tau Θθ Theta Υυ Upsilon Ιι Iota Φφ Phi Κκ Kappa Χχ Chi Λλ Lambda Ψψ Psi Μμ Mu Ωω Omega
History
Archaic local variants Diacritics Ligatures Numerals ϛ (6) ϟ (90) ϡ (900)
Use in other languages
Bactrian Coptic Albanian
Related topics
Use as scientific symbols
Book  Category  Commons
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Lambda (uppercase Λ, lowercase λ; Greek: Λάμ(β)δα lam(b)da) is the 11th letter of the Greek alphabet. In the system ofGreek numerals lambda has a value of 30. Lambda is related to the Phoenician letter Lamed . Letters in other alphabetsthat stemmed from lambda include the Latin L and the Cyrillic letter El (Л, л). The ancient grammarians and dramatists give evidence to the pronunciation as [laːbdaː] (λάβδα) in Classical Greek times.^[1] In Modern Greek the name of the letter, Λάμδα, is pronounced [lamða]; the spoken letter itself has the sound of [l] as with Latinate "L".

The Greek alphabet on a black figure vessel, with a Phoenician-lamed-shaped lambda. (The gamma has the shape of modern lambda.)

Symbol[edit]

Upper-case letter Λ[edit]

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• The lambda particle is a type of subatomic particle in subatomic particle physics.
• Lambda is the set of logical axioms in the axiomatic method of logical deduction in first-order logic.
• Lambda was used as a shield pattern by the Spartan Army. This stood for Lacedaemon, (Λακεδαίμων, Lakedaímōn), the name of the region of Sparta.
• Lambda is the von Mangoldt function in mathematical number theory.
• In statistics, Wilks's lambda is used in multivariate analysis of variance (MANOVA analysis) to compare group means on a combination of dependent variables.
• In the spectral decomposition of matrices, lambda indicates the diagonal matrix of the eigenvalues of the matrix (mathematics).
• In computer science, lambda is the time window over which a process is observed for determining the working memory set for a digital computer's virtual memory management.
• In astrophysics, lambda represents the likelihood that a small body will encounter a planet or a dwarf planet leading to a deflection of a significant magnitude. An object with a large value of lambda is expected to have cleared its neighborhood, satisfying the current definition of a planet.
• In crystal optics, lambda is used to represent the period of a lattice.
• In NATO military operations, a chevron (a capital lambda symbol) is painted on the vehicles of this military alliance for identification.
• In chemistry there are Δ (delta) and Λ (lambda) isomers, see: coordination complex
• In electrochemistry, lambda denotes the "equivalent conductance" of an electrolyte solution.
• In cosmology, lambda is the symbol for the cosmological constant.
• In optics, lambda denotes the grating pitch of a Bragg reflector.
• In handwritten Russian, this letter represents Л in both uppercase and lowercase formats.

Lower-case letter λ[edit]

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Lower-case lambda

• In evolutionary algorithms, λ indicates the number of offspring that would be generated from μ current population in each generation. The terms μ and λ are originated from Evolution strategy notation.
• Lambda indicates the wavelength of any wave, especially in physics, electronics engineering, and mathematics.
• Lambda indicates the radioactivity decay constant in nuclear physics and radioactivity. This constant is very simply related (by a multiplicative constant) to the half-life of any radioactive material.
• In probability theory, lambda represents the density of occurrences within a time interval, as modeled by the Poisson distribution.
• In mathematical logic and computer science, lambda is used to introduce anonymous functions expressed with the concepts of lambda calculus.
• Lambda is a symbol for one microliter (1 μL), that is, one cubic millimetre (1 mm³). This use is currently deprecated.
• Lambda indicates an eigenvalue in the mathematics of linear algebra.
• In the physics of electric fields, lambda sometimes indicates the linear charge density of a uniform line of electric charge (measured incoulombs per meter).
• Lambda denotes a Lagrange multiplier in multi-dimensional calculus.
• In solid-state electronics, lambda indicates the channel length modulation parameter of a MOSFET.
• There is a lambda phage virus in biology.
• In ecology, lambda denotes the long-term intrinsic growth rate of a population. This value is often calculated as the dominant eigenvalue of the age/size classmatrix (mathematics).
• In formal language theory and in computer science, lambda denotes the empty string.^{[citation needed]}
• Lambda is a nonstandard symbol in the International Phonetic Alphabet.
• In telecommunications, lambda indicates the wavelength in a wavelength-division multiplexing optical communications system. This is actually a form of the long-established concept of frequency-division multiplexing.
• Lambda denotes the Lebesgue measure in mathematical set theory.
• The Goodman and Kruskal's lambda in statistics indicates the proportional reduction in error when one variable's values are used to predict the values of another variable.
• Lambda denotes the oxygen sensor in a vehicle that measures the air-to-fuel ratio in the exhaust gases of an internal-combustion engine.
• A Lambda 4S solid-fuel rocket was used to launch Japan's first orbital satellite in 1970.^[4]
• Lambda denotes the failure rate of devices and systems in reliability theory, and it is measured in failure events per hour. Numerically, this lambda is also the reciprocal of the mean time between failures.
• In criminology, lambda denotes an individual's frequency of offenses.
• In cartography and navigation, lambda denotes the longitude of a location.
• Lambda is the symbol of the musician Richard D. James or Aphex Twin.
• Lambda denotes Christopher Langton's parameter for the classification of Stephen Wolfram's classes of cellular automata.
• In electrochemistry, lambda also denotes the ionic conductance of a given ion (The composition of the ion is generally shown as a subscript to the lambda character).
• In neurobiology, lambda denotes the length constant (or exponential rate of decay) of the electric potential across the cell membrane along a length of a nerve cell's axon.
• In the science and technology of heat transfer, lambda denotes the heat of vaporization per mole of material (a.k.a. its "latent heat").^[5]
• In the technology and science of celestial navigation, lambda denotes the longitude as opposed to the Roman letter "L", which denotes the latitude.
• King Louis XIII of France used the letter lambda as his personal symbol rather than monogram.
• In Volvo automobiles, lambda denotes an engine, fuel, or ignition system failure.
• A block style Lambda is used as a recurring symbol in the Valve computer game series Half-Life, referring to the Lambda complex of the fictional Black Mesa Research Facility.
• The lambda was selected as a symbol by the Gay Activists Alliance of New York in 1970, and declared the international symbol for gay and lesbian rights by the International Gay Rights Congress in Edinburgh, Scotland, in 1974.
• The "lambda sign" is used for diagnosis of dichorionic twins in obstetric ultrasonography
• In bifurcation theory, lambda is used to parameterize a family of differential equations

Lambda as a programming construct[edit]

• In programming languages such as Lisp, Python and Ruby lambda is an operator used to denote anonymous functions or closures, following the usage oflambda calculus. An example of this use of lambda in the Python language is this section of computer code that sorts a list alphabetically by the last character of each entry:

>>> list = ['woman', 'man', 'horse', 'boat', 'plane', 'dog']
>>> sorted(list, key = lambda word: (word[-1]))
['horse', 'plane', 'dog', 'woman', 'man', 'boat']

• In the C# programming language a lambda expression is an anonymous function that can contain expressions and statements.^[6]
• The language Unlambda is a functional programming language based upon combinatory logic, a simplification of the lambda calculus that does not involve the lambda at all, hence the un- prefix.
• An automotive oxygen sensor (O₂ sensor) is also known as a lambda probe, sensor, sond, or sonde.
• Lambda is used in art and photography to refer to a digital Type C print, or to the equipment that is used to produce it.
• Lambda was used by Pythagoras to denote the "Lambda number sequence" 1, 2, 3, 4, 9, 8, 27, ...,(sequence A098293 in OEIS) formed by the integers of the form 2ⁱ and 3ⁱ, for nonnegative integer i.^{[citation needed]}
• In the study of gasoline engines, Lambda sometimes refers to the air/fuel mixture going into the engine.

Lambda as a name[edit]

• Stargate SG-1 uses a modified upper-case lambda, with a small circle above the apex, to indicate Earth. This symbol has since become associated with the entire franchise.^[7][8]
• The popular science fiction universe of Star Wars uses a transport vehicle known as the Lambda-class shuttle that when viewed forward has the shape of the lowercase lambda.^[9]
• Lambda is occasionally used in graphic design to represent a stylised 'A'. Examples include the Disney movie Atlantis: The Lost Empire, the logo of the bandAngels & Airwaves, the logo of the band Dream Theater, the logo of electronics company Samsung, and the logo of the engineering consultancy Atkins. Conversely, the name of the band Λucifer (pronounced lucifer) is sometimes spelled Aucifer.
• The upper-case lambda is used as the alias of Providence, Rhode Island based musician Xavier Valentine.^[10]
• The Half-Life franchise of video games uses an encircled block style lower-case lambda as the franchise logo (Half-Life 2 adds the numeral 2 into the logo assuperscript), prominently featured on the chest of Gordon Freeman's (the protagonist) powered armor, known as an HEV suit. In the first game, the logo appears at the entrances of the Black Mesa Research Facility's Lambda Complex, which conducted teleportation research. In Half-Life 2 and its Episodes, the encircled block lambda is the universal symbol of the Resistance, often spraypainted to mark the location of safehouses and hidden supply caches; full-time Resistance members wear armbands containing a lower-case lambda without the circle.
• In the 2D fighting game series BlazBlue, a recurring character named Lambda-11 appears in the various games' story modes and as a playable character.
• Several LGBT rights organizations, such as Lambda Legal and the Lambda Literary Award derive their names from the use of a lower-case lambda as a symbol for LGBT rights.
• In the RPG game Tales of Graces, originally made for the Wii, Lambda is the name of the main story's antagonist.
• There is a PlayStation Vita game known as Cytus Lambda.
• The musical group Axwell Λ Ingrosso use the lambda as symbol in their name.