Bringen Sie eine gute Kamera und reichlich Abenteuerlust mit – der Ring of Kerry entführt Sie in einige der atemberaubendsten Landschaften der grünen Insel. Wohl kaum eine Straße ist in Irland derart berühmt wie der Ring of Kerry. Er vereint malerische Aussichtspunkte mit einem umfangreichen Kulturangebot. Der „ring of fire“ ist ein Vulkangürtel, der den Pazifischen Ozean umringt; er ist Abbild unvergleichlicher Naturgewalten. Eine Parallele? Durchaus. Zwar wurde.
LEISTUNGENThe Ring of Five (Ro5) is both a regional (European) and a topical. (Atmosphere) network dedicated to airborne radionuclide at trace levels in the atmosphere. Richard WAGNER SIEGFRIED PART III THE RING OF THE NIBELUNGEN for Soli, Chorus and Orchestra with German and English text and a Table of Motifs. Der „ring of fire“ ist ein Vulkangürtel, der den Pazifischen Ozean umringt; er ist Abbild unvergleichlicher Naturgewalten. Eine Parallele? Durchaus. Zwar wurde.
Ring Of Search form VideoBankers Ask Trump For Priority Access To COVID Vaccine
Described as being akin to a neighborhood watch , it allows users to crowdsource information on and discuss safety and security concerns in their area.
The service allows users to share footage captured from Ring products, so that others can help to identify suspects. All user posts are anonymous and do not include specific location information, and are moderated to remove off-topic content in contrast to services such as Nextdoor , it focuses exclusively on crime and safety.
Ring also has partnerships with local police departments in some cities to incorporate Neighbors into their crime monitoring processes, and they are also able to make official posts for distribution on the service.
Ring has credited the service with having helped to solve crimes, and noted that activity on the service surged in California regions affected by wildfires in November Amazon disclosed Ring's criteria for accepting requests from police departments for video footage shared to the Neighbors portal in a response to Massachusetts Senator Ed Markey on November 1, Each police request must be associated with a case number and submitted individually, although no evidence is needed.
Ring provides at most 12 hours of footage recorded within the previous 45 days in a maximum search area of 0.
Markey criticized Amazon's response, describing Ring as "an open door for privacy and civil liberty violations". Police departments may access user-generated footage through the Ring Neighborhoods portal by request, using a map interface.
After a police officer requests video from a list of houses, Ring sends all affected users automated messages requesting permission to release the footage.
TechHive gave the second-generation Ring doorbell a 4 out of 5, noting improvements in hardware and ease of installation over the first-generation model, but criticizing a lack of printed and online documentation.
Digital rights advocacy group Fight for the Future criticized Ring for using its cameras and Neighbors app to build a private surveillance network via partnerships with local law enforcement agencies, which encourage them to promote the products.
The group stated that these partnerships "undermine our democratic process and basic civil liberties ". The organization said that Ring, as well as Neighbors and similar "neighborhood watch" apps such as Citizen and Nextdoor , "facilitate reporting of so-called 'suspicious' behavior that really amounts to racial profiling.
In November of , a pilot program in Jackson, Mississippi enabled participating Ring users to enable police to livestream their cameras at anytime.
In a December test, Motherboard found that Ring's software did not implement "basic security features", allowing the publication to access a Ring account from IP addresses based in multiple countries without warning the user.
Nextdoor network leaks metadata about the footage posted in videos and "crime alerts". This metadata, combined with public city map data, is frequently sufficient to discover the exact location of the Ring dorbell or a camera.
In one experiment, Gizmodo located 20 thousand devices based on information collected scraped from the app over a period of month.
University researchers were able to locate thousand devices using data spanning back to Amazon enabled by default Amazon Sidewalk on supported Ring and Alexa devices.
This feature allows devices owned by different people to communicate and transmit data without consent of either owner. Gizmodo criticized Amazon Sidewalk for allowing strangers to connect to Ring owners' home Wi-Fi network.
On January 27, , the Electronic Frontier Foundation concluded that the Ring doorbell app for Android was sending identifiable personal information— including names, IP addresses, mobile network carriers, persistent IDs and sensor data —to four analytics and marketing companies: Facebook , Mixpanel , AppsFlyer and branch.
From Wikipedia, the free encyclopedia. Home security products manufacturer. Main article: Neighbors app.
Main article: Amazon Sidewalk. Bloomberg L. Retrieved April 9, Retrieved June 12, Christopher; Frey, Christopher D.
Retrieved Ring Help. Apartment Therapy. Tech News Daily. Archived from the original on January 26, August 19, Retrieved December 13, Business Insider.
Retrieved March 25, It consists of a set equipped with two binary operations that generalize the arithmetic operations of addition and multiplication.
Through this generalization, theorems from arithmetic are extended to non-numerical objects such as polynomials , series , matrices and functions.
By extension from the integers , the abelian group operation is called addition and the second binary operation is called multiplication.
Whether a ring is commutative or not that is, whether the order in which two elements are multiplied changes the result or not has profound implications on its behavior as an abstract object.
As a result, commutative ring theory, commonly known as commutative algebra , is a key topic in ring theory.
Its development has been greatly influenced by problems and ideas occurring naturally in algebraic number theory and algebraic geometry.
Examples of commutative rings include the set of integers equipped with the addition and multiplication operations, the set of polynomials equipped with their addition and multiplication, the coordinate ring of an affine algebraic variety , and the ring of integers of a number field.
The conceptualization of rings began in the s and was completed in the s. Key contributors include Dedekind , Hilbert , Fraenkel , and Noether.
Rings were first formalized as a generalization of Dedekind domains that occur in number theory , and of polynomial rings and rings of invariants that occur in algebraic geometry and invariant theory.
Afterward, they also proved to be useful in other branches of mathematics such as geometry and mathematical analysis.
The familiar properties for addition and multiplication of integers serve as a model for the axioms for rings. This article adopts the convention that, unless otherwise stated, a ring is assumed to have such an identity.
Authors who follow this convention sometimes refer to a structure satisfying all the axioms except the requirement that there exists a multiplicative identity element as a rng commonly pronounced rung and sometimes as a pseudo-ring.
Although ring addition is commutative , ring multiplication is not required to be commutative: ab need not necessarily equal ba.
Rings that also satisfy commutativity for multiplication such as the ring of integers are called commutative rings.
Books on commutative algebra or algebraic geometry often adopt the convention that ring means commutative ring , to simplify terminology.
In a ring, multiplicative inverses are not required to exist. A non zero commutative ring in which every nonzero element has a multiplicative inverse is called a field.
The additive group of a ring is the underlying set equipped with only the operation of addition. Although the definition assumes that the additive group is abelian, this can be inferred from the other ring axioms.
Although most modern authors require multiplication in a ring to be associative, there are a few who do not.
Then Z 4 is a ring: each axiom follows from the corresponding axiom for Z. The set of 2-by-2 matrices with real number entries is written.
With the operations of matrix addition and matrix multiplication , this set satisfies the above ring axioms. More generally, for any ring R , commutative or not, and any nonnegative integer n , one may form the ring of n -by- n matrices with entries in R : see Matrix ring.
The study of rings originated from the theory of polynomial rings and the theory of algebraic integers. But Dedekind did not use the term "ring" and did not define the concept of a ring in a general setting.
The term "Zahlring" number ring was coined by David Hilbert in and published in According to Harvey Cohn, Hilbert used the term for a ring that had the property of "circling directly back" to an element of itself.
The first axiomatic definition of a ring was given by Adolf Fraenkel in ,   but his axioms were stricter than those in the modern definition.
For instance, he required every non-zero-divisor to have a multiplicative inverse. Fraenkel required a ring to have a multiplicative identity 1,  whereas Noether did not.
Most or all books on algebra   up to around followed Noether's convention of not requiring a 1. Starting in the s, it became increasingly common to see books including the existence of 1 in the definition of ring, especially in advanced books by notable authors such as Artin,  Atiyah and MacDonald,  Bourbaki,  Eisenbud,  and Lang.
Faced with this terminological ambiguity, some authors have tried to impose their views, while others have tried to adopt more precise terms.
In the first category, we find for instance Gardner and Wiegandt, who argue that if one requires all rings to have a 1, then some consequences include the lack of existence of infinite direct sums of rings, and the fact that proper direct summands of rings are not subrings.
They conclude that "in many, maybe most, branches of ring theory the requirement of the existence of a unity element is not sensible, and therefore unacceptable.
In the second category, we find authors who use the following terms:  . One example of a nilpotent element is a nilpotent matrix.
A nilpotent element in a nonzero ring is necessarily a zero divisor. One example of an idempotent element is a projection in linear algebra.
A subset S of R is called a subring if any one of the following equivalent conditions holds:. For example, the ring Z of integers is a subring of the field of real numbers and also a subring of the ring of polynomials Z [ X ] in both cases, Z contains 1, which is the multiplicative identity of the larger rings.
On the other hand, the subset of even integers 2 Z does not contain the identity element 1 and thus does not qualify as a subring of Z ; one could call 2 Z a subrng , however.
An intersection of subrings is a subring. Given a subset E of R , the smallest subring of R containing E is the intersection of all subrings of R containing E , and it is called the subring generated by E.
For a ring R , the smallest subring of R is called the characteristic subring of R. If n is the smallest positive integer such that this occurs, then n is called the characteristic of R.
More generally, given a subset X of R , let S be the set of all elements in R that commute with every element in X.
Then S is a subring of R , called the centralizer or commutant of X. The center is the centralizer of the entire ring R.
Elements or subsets of the center are said to be central in R ; they each individually generate a subring of the center.
The definition of an ideal in a ring is analogous to that of normal subgroup in a group. But, in actuality, it plays a role of an idealized generalization of an element in a ring; hence, the name "ideal".
Like elements of rings, the study of ideals is central to structural understanding of a ring. Let R be a ring.
A subset I is said to be a two-sided ideal or simply ideal if it is both a left ideal and right ideal. A one-sided or two-sided ideal is then an additive subgroup of R.
Similarly, one can consider the right ideal or the two-sided ideal generated by a subset of R. For example, the set of all positive and negative multiples of 2 along with 0 form an ideal of the integers, and this ideal is generated by the integer 2.
In fact, every ideal of the ring of integers is principal. Like a group, a ring is said to be simple if it is nonzero and it has no proper nonzero two-sided ideals.
A commutative simple ring is precisely a field. Rings are often studied with special conditions set upon their ideals.
For example, a ring in which there is no strictly increasing infinite chain of left ideals is called a left Noetherian ring. A ring in which there is no strictly decreasing infinite chain of left ideals is called a left Artinian ring.
It is a somewhat surprising fact that a left Artinian ring is left Noetherian the Hopkins—Levitzki theorem.
The integers, however, form a Noetherian ring which is not Artinian. For commutative rings, the ideals generalize the classical notion of divisibility and decomposition of an integer into prime numbers in algebra.
A ring homomorphism is said to be an isomorphism if there exists an inverse homomorphism to f that is, a ring homomorphism that is an inverse function.
Any bijective ring homomorphism is a ring isomorphism. A ring homomorphism between the same ring is called an endomorphism and an isomorphism between the same ring an automorphism.
The kernel is a two-sided ideal of R. The image of f , on the other hand, is not always an ideal, but it is always a subring of S.
To give a ring homomorphism from a commutative ring R to a ring A with image contained in the center of A is the same as to give a structure of an algebra over R to A which in particular gives a structure of an A -module.
The quotient ring of a ring is analogous to the notion of a quotient group of a group. The last fact implies that actually any surjective ring homomorphism satisfies the universal property since the image of such a map is a quotient ring.
The concept of a module over a ring generalizes the concept of a vector space over a field by generalizing from multiplication of vectors with elements of a field scalar multiplication to multiplication with elements of a ring.
This operation is commonly denoted multiplicatively and called multiplication. The axioms of modules are the following: for all a , b in R and all x , y in M , we have:.
When the ring is noncommutative these axioms define left modules ; right modules are defined similarly by writing xa instead of ax.
Although similarly defined, the theory of modules is much more complicated than that of vector space, mainly, because, unlike vector spaces, modules are not characterized up to an isomorphism by a single invariant the dimension of a vector space.
In particular, not all modules have a basis. Using this and denoting repeated addition by a multiplication by a positive integer allows identifying abelian groups with modules over the ring of integers.
In particular, every ring is an algebra over the integers. Let R and S be rings. Then the Chinese remainder theorem says there is a canonical ring isomorphism:.
A "finite" direct product may also be viewed as a direct sum of ideals. Clearly the direct sum of such ideals also defines a product of rings that is isomorphic to R.
Equivalently, the above can be done through central idempotents. Assume R has the above decomposition. Then we can write.
Again, one can reverse the construction. An important application of an infinite direct product is the construction of a projective limit of rings see below.
Another application is a restricted product of a family of rings cf. Given a symbol t called a variable and a commutative ring R , the set of polynomials.
It is called the polynomial ring over R. Given an element x of S , one can consider the ring homomorphism.
Example: let f be a polynomial in one variable, that is, an element in a polynomial ring R. The substitution is a special case of the universal property of a polynomial ring.
To give an example, let S be the ring of all functions from R to itself; the addition and the multiplication are those of functions.
Let x be the identity function. The universal property says that this map extends uniquely to. The resulting map is injective if and only if R is infinite.
Let k be an algebraically closed field. In particular, many local problems in algebraic geometry may be attacked through the study of the generators of an ideal in a polynomial ring.
Gröbner basis. There are some other related constructions. A formal power series ring does not have the universal property of a polynomial ring; a series may not converge after a substitution.
The important advantage of a formal power series ring over a polynomial ring is that it is local in fact, complete. Let R be a ring not necessarily commutative.
The set of all square matrices of size n with entries in R forms a ring with the entry-wise addition and the usual matrix multiplication.
It is called the matrix ring and is denoted by M n R. The Artin—Wedderburn theorem states any semisimple ring cf. A ring R and the matrix ring M n R over it are Morita equivalent : the category of right modules of R is equivalent to the category of right modules over M n R.
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