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Signature (computer Science)
A signature is a mark used to confirm a person's identity or intent. Signature may also refer to: Businesses and organizations * Signature (charity), for deaf communication activities in the UK * Signature, a clothing brand of Levi Strauss & Co. * Signature (dance group) English Bhangra dance duo Suleman Mirza and Madhu Singh * Signature (typography journal), a 20th-century British journal * Signature (whisky), an Indian whisky brand * Signature Books, a publisher of Mormon works * Signature Flight Support, a British fixed-base operator * Signatures Restaurant, former restaurant once owned by Washington lobbyist Jack Abramoff * Signature School, a charter school in Evansville, Indiana * Signature Team, a French motor racing team * Signature Theatres, a movie theatre chain Computing * Signature block, text automatically appended at the bottom of electronic messages * Electronic signature, a digital form of identity or intent validation * File signature, data used to identify o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signatures
A signature (; from , "to sign") is a depiction of someone's name, nickname, or even a simple "X" or other mark that a person writes on documents as a proof of identity and intent. Signatures are often, but not always, handwritten or stylized. The writer of a signature is a signatory or signer. Similar to a handwritten signature, a signature work describes the work as readily identifying its creator. A signature may be confused with an autograph, which is chiefly an artistic signature. This can lead to confusion when people have both an autograph and signature and as such some people in the public eye keep their signatures private whilst fully publishing their autograph. Function and types Identification The traditional function of a signature is to permanently affix to a document a person's uniquely personal, undeniable self-identification as physical evidence of that person's personal witness and certification of the content of all, or a specified part, of the documen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
XML Signature
XML Signature (also called ''XMLDSig'', ''XML-DSig'', ''XML-Sig'') defines an XML syntax for digital signatures and is defined in the W3C recommendationbr>XML Signature Syntax and Processing Functionally, it has much in common with PKCS #7 but is more extensible and geared towards signing XML documents. It is used by various Web technologies such as SOAP, SAML, and others. XML signatures can be used to sign data–a resource–of any type, typically XML documents, but anything that is accessible via a URL can be signed. An XML signature used to sign a resource outside its containing XML document is called a detached signature; if it is used to sign some part of its containing document, it is called an enveloped signature; if it contains the signed data within itself it is called an enveloping signature. Structure An XML Signature consists of a Signature element in the http://www.w3.org/2000/09/xmldsig# namespace. The basic structure is as follows: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (Moya Brennan Album)
''Signature'' is a music album by Irish musician] Moya Brennan. This is her seventh solo album to be released. It was released on the 9 October 2006 in Ireland, the UK and the Netherlands. The worldwide release was scheduled for early 2007, but was temporarily delayed until 25 September 2007. Release Announcement from her official site: ''Sunday, 16 July 2006'' "In the last few days Moya has completed the recording and mixing of her new album entitled Signature. Release is planned in Europe for late September but check back here for release dates in specific places. We can now reveal the track listing for the album (and we anticipate that some of the titles will give rise to discussion!)" Snip from her official website on 'Signature' Signature looks back over a life less ordinary and portrays Moya's experiences through a collection of twelve superb tracks. Musically sharp and finely tuned, the album cleverly treads a fine line between the contemporary and the traditional whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Key Signature
In Western musical notation, a key signature is a set of sharp (), flat (), or rarely, natural () symbols placed on the staff at the beginning of a section of music. The initial key signature in a piece is placed immediately after the clef at the beginning of the first line. If the piece contains a section in a different key, the new key signature is placed at the beginning of that section. In a key signature, a sharp or flat symbol on a line or space of the staff indicates that the note represented by that line or space is to be played a semitone higher (sharp) or lower (flat) than it would otherwise be played. This applies through the rest of the piece or until another key signature appears. Each symbol applies to comparable notes in all octaves—for example, a flat on the fourth space of the treble staff (as in the diagram) indicates that all notes notated as Es are played as E-flats, including those on the bottom line of the staff. Most of this article addres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Metric Signature
In mathematics, the signature of a metric tensor ''g'' (or equivalently, a real quadratic form thought of as a real symmetric bilinear form on a finite-dimensional vector space) is the number (counted with multiplicity) of positive, negative and zero eigenvalues of the real symmetric matrix of the metric tensor with respect to a basis. In relativistic physics, ''v'' conventionally represents the number of time or virtual dimensions, and ''p'' the number of space or physical dimensions. Alternatively, it can be defined as the dimensions of a maximal positive and null subspace. By Sylvester's law of inertia these numbers do not depend on the choice of basis and thus can be used to classify the metric. It is denoted by three integers , where v is the number of positive eigenvalues, p is the number of negative ones and r is the number of zero eigenvalues of the metric tensor. It can also be denoted implying ''r'' = 0, or as an explicit list of signs of eigenvalues s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (matrix)
Sylvester's law of inertia is a theorem in matrix algebra about certain properties of the coefficient matrix of a real quadratic form that remain invariant under a change of basis. Namely, if A is a symmetric matrix, then for any invertible matrix S, the number of positive, negative and zero eigenvalues (called the inertia of the matrix) of D=SAS^\mathrm is constant. This result is particularly useful when D is diagonal, as the inertia of a diagonal matrix can easily be obtained by looking at the sign of its diagonal elements. This property is named after James Joseph Sylvester who published its proof in 1852. Statement Let A be a symmetric square matrix of order n with real entries. Any non-singular matrix S of the same size is said to transform A into another symmetric matrix , also of order , where S^\mathrm is the transpose of . It is also said that matrices A and B are congruent. If A is the coefficient matrix of some quadratic form of , then B is the matrix for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Prime Signature
In mathematics, the prime signature of a number is the multiset of (nonzero) exponents of its prime factorization In mathematics, integer factorization is the decomposition of a positive integer into a product of integers. Every positive integer greater than 1 is either the product of two or more integer factors greater than 1, in which case it is a comp .... The prime signature of a number having prime factorization p_1^p_2^ \dots p_n^ is the multiset \left \. For example, all prime numbers have a prime signature of , the Square number, squares of primes have a prime signature of , the products of 2 distinct primes have a prime signature of and the products of a square of a prime and a different prime (e.g. 12, 18, 20, ...) have a prime signature of . Properties The divisor function τ(''n''), the Möbius function ''μ''(''n''), the number of distinct prime divisors ω(''n'') of ''n'', the number of prime divisors Ω(''n'') of ''n'', the indicator function of the squar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature Of A Knot
The signature of a knot is a topological invariant in knot theory. It may be computed from the Seifert surface. Given a knot ''K'' in the 3-sphere, it has a Seifert surface ''S'' whose boundary is ''K''. The Seifert form of ''S'' is the pairing \phi : H_1(S) \times H_1(S) \to \mathbb Z given by taking the linking number \operatorname(a^+,b^-) where a, b \in H_1(S) and a^+, b^- indicate the translates of ''a'' and ''b'' respectively in the positive and negative directions of the normal bundle to ''S''. Given a basis b_1,...,b_ for H_1(S) (where ''g'' is the genus of the surface) the Seifert form can be represented as a ''2g''-by-''2g'' Seifert matrix ''V'', V_=\phi(b_i,b_j). The signature of the matrix V+V^t, thought of as a symmetric bilinear form, is the signature of the knot ''K''. Slice knots are known to have zero signature. The Alexander module formulation Knot signatures can also be defined in terms of the Alexander module of the knot complement. Let X be the universa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (topology)
In the field of topology, the signature is an integer invariant which is defined for an oriented manifold ''M'' of dimension divisible by four. This invariant of a manifold has been studied in detail, starting with Rokhlin's theorem for 4-manifolds, and Hirzebruch signature theorem. Definition Given a connected and oriented manifold ''M'' of dimension 4''k'', the cup product gives rise to a quadratic form ''Q'' on the 'middle' real cohomology group :H^(M,\mathbf). The basic identity for the cup product :\alpha^p \smile \beta^q = (-1)^(\beta^q \smile \alpha^p) shows that with ''p'' = ''q'' = 2''k'' the product is symmetric. It takes values in :H^(M,\mathbf). If we assume also that ''M'' is compact, Poincaré duality identifies this with :H_(M,\mathbf) which can be identified with \mathbf. Therefore the cup product, under these hypotheses, does give rise to a symmetric bilinear form on ''H''2''k''(''M'',''R''); and therefore to a quadratic form ''Q''. The form ''Q'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (quadratic Form)
In mathematics, a quadratic form is a polynomial with terms all of degree two ("form" is another name for a homogeneous polynomial). For example, 4x^2 + 2xy - 3y^2 is a quadratic form in the variables and . The coefficients usually belong to a fixed field , such as the real or complex numbers, and one speaks of a quadratic form ''over'' . Over the reals, a quadratic form is said to be '' definite'' if it takes the value zero only when all its variables are simultaneously zero; otherwise it is ''isotropic''. Quadratic forms occupy a central place in various branches of mathematics, including number theory, linear algebra, group theory (orthogonal groups), differential geometry (the Riemannian metric, the second fundamental form), differential topology ( intersection forms of manifolds, especially four-manifolds), Lie theory (the Killing form), and statistics (where the exponent of a zero-mean multivariate normal distribution has the quadratic form -\mathbf^\mathsf\boldsymbol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (permutation)
In mathematics, when ''X'' is a finite set with at least two elements, the permutations of ''X'' (i.e. the bijective functions from ''X'' to ''X'') fall into two classes of equal size: the even permutations and the odd permutations. If any total ordering of ''X'' is fixed, the parity (oddness or evenness) of a permutation \sigma of ''X'' can be defined as the parity of the number of inversions for ''σ'', i.e., of pairs of elements ''x'', ''y'' of ''X'' such that and . The sign, signature, or signum of a permutation ''σ'' is denoted sgn(''σ'') and defined as +1 if ''σ'' is even and −1 if ''σ'' is odd. The signature defines the alternating character of the symmetric group S''n''. Another notation for the sign of a permutation is given by the more general Levi-Civita symbol (''ε''''σ''), which is defined for all maps from ''X'' to ''X'', and has value zero for non-bijective maps. The sign of a permutation can be explicitly expressed as : where ''N''('' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Signature (logic)
In logic, especially mathematical logic, a signature lists and describes the non-logical symbols of a formal language. In universal algebra, a signature lists the operations that characterize an algebraic structure. In model theory, signatures are used for both purposes. They are rarely made explicit in more philosophical treatments of logic. Definition Formally, a (single-sorted) signature can be defined as a 4-tuple \sigma = \left(S_, S_, S_, \operatorname\right), where S_ and S_ are disjoint sets not containing any other basic logical symbols, called respectively * '' function symbols'' (examples: +, \times), * ''s'' or '' predicates'' (examples: \,\leq, \, \in), * '' constant symbols'' (examples: 0, 1), and a function \operatorname : S_ \cup S_ \to \N which assigns a natural number called ''arity'' to every function or relation symbol. A function or relation symbol is called n-ary if its arity is n. Some authors define a nullary (0-ary) function symbol as ''constant symbol'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
