Operator normIn mathematics, the operator norm measures the "size" of certain linear operators by assigning each a real number called its . Formally, it is a norm defined on the space of bounded linear operators between two given normed vector spaces. Informally, the operator norm of a linear map is the maximum factor by which it "lengthens" vectors. Given two normed vector spaces and (over the same base field, either the real numbers or the complex numbers ), a linear map is continuous if and only if there exists a real number such that The norm on the left is the one in and the norm on the right is the one in .
Opera (web browser)Opera is a multi-platform web browser developed by its namesake company Opera. The browser is based on Chromium, but distinguishes itself from other Chromium-based browsers (Chrome, Edge, etc.) through its user interface and other features. Opera was initially released on 10 April 1995, making it one of the oldest desktop web browsers still actively developed. It was commercial software for its first ten years and had its own proprietary layout engine, Presto. In 2013, it switched from the Presto engine to Chromium.
Metropolitan OperaThe Metropolitan Opera (commonly known as the Met) is an American opera company based in New York City, currently resident at the Metropolitan Opera House at Lincoln Center, situated on the Upper West Side of Manhattan. The company is operated by the non-profit Metropolitan Opera Association, with Peter Gelb as general manager. As of 2018, the company's current music director is Yannick Nézet-Séguin. The Met was founded in 1883 as an alternative to the previously established Academy of Music opera house and debuted the same year in a new building on 39th and Broadway (now known as the "Old Met").
French operaFrench opera is both the art of opera in France and opera in the French language. It is one of Europe's most important operatic traditions, containing works by composers of the stature of Rameau, Berlioz, Gounod, Bizet, Massenet, Debussy, Ravel, Poulenc and Messiaen. Many foreign-born composers have played a part in the French tradition, including Lully, Gluck, Salieri, Cherubini, Spontini, Meyerbeer, Rossini, Donizetti, Verdi and Offenbach.
Comic operaComic opera, sometimes known as light opera, is a sung dramatic work of a light or comic nature, usually with a happy ending and often including spoken dialogue. Forms of comic opera first developed in late 17th-century Italy. By the 1730s, a new operatic genre, opera buffa, emerged as an alternative to opera seria. It quickly made its way to France, where it became opéra comique, and eventually, in the following century, French operetta, with Jacques Offenbach as its most accomplished practitioner.
MailThe mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal systems have generally been established as a government monopoly, with a fee on the article prepaid. Proof of payment is usually in the form of an adhesive postage stamp, but a postage meter is also used for bulk mailing. Postal authorities often have functions aside from transporting letters.
History of the Opera web browserThe history of the Opera web browser began in 1994 when it was started as a research project at Telenor, the largest Norwegian telecommunications company. In 1995, the project branched out into a separate company named Opera Software ASA, with the first publicly available version released in 1996. Opera has undergone extensive changes and improvements, and introduced notable features such as Speed Dial. Until version 2.0, the Opera browser was called MultiTorg Opera (version 1.
Opera (company)Opera is a Norwegian multinational technology conglomerate holding company headquartered in Oslo, Norway with additional offices in Europe, China, and Africa. The company's total user base, including users of its desktop browsers, mobile browsers and other services exceeds 380 million monthly active users. In 2016, Opera was acquired by an investment group led by a Chinese consortium. On July 27, 2018, Opera Software went public on the NASDAQ stock exchange, raising $115 million in its initial public offering.
Royal MailRoyal Mail Group Limited, trading as Royal Mail, is a British postal service and courier company, originally established in 1516 as a government department. It is owned by International Distributions Services. It operates the brands Royal Mail (letters and parcels) and Parcelforce Worldwide (parcels). The group used the name Consignia for a brief period in the early 2000s. The company provides mail collection and delivery services throughout the UK.
Greenhouse gas emissionsGreenhouse gas emissions (abbreviated as GHG emissions) from human activities strengthen the greenhouse effect, contributing to climate change. Carbon dioxide (), from burning fossil fuels such as coal, oil, and natural gas, is one of the most important factors in causing climate change. The largest emitters are China followed by the US, although the United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies.
AC powerIn an electric circuit, instantaneous power is the time rate of flow of energy past a given point of the circuit. In alternating current circuits, energy storage elements such as inductors and capacitors may result in periodic reversals of the direction of energy flow. Its SI unit is the watt. The portion of instantaneous power that, averaged over a complete cycle of the AC waveform, results in net transfer of energy in one direction is known as instantaneous active power, and its time average is known as active power or real power.
Opera houseAn opera house is a theatre building used for performances of opera. It usually includes a stage, an orchestra pit, audience seating, and backstage facilities for costumes and building sets. While some venues are constructed specifically for operas, other opera houses are part of larger performing arts centers. Indeed, the term opera house is often used as a term of prestige for any large performing-arts center.
