In many problems, we often divide a large space into smaller areas. For instance, a house is divided into rooms, a nation into states, a type of quantity into numbers, and so on. Each of these smaller areas (room, state, number) is next to other small areas (other rooms/states/numbers). The places where the areas meet are connections. If we write down on paper a list of spaces, and the connections between them, we have written down a description of a space -- a topological space. All topological spaces have the same properties such as connections, and are made of the same structure (a list of smaller areas). This makes it easier to study how spaces behave. It also makes it easier to write algorithms. For instance, to program a robot to navigate a house, we simply give it a list of rooms, the connections between each room (doors), and an algorithm that can work out which rooms to go through to reach any other room. For more examples of this type of problem, look at Graph theory.
We can go further by creating subdivisions of subdivisions of space. For instance, a nation divided into states, divided into counties, divided into city boundaries, and so on. All this kind of information can be described using topology.
1933
1933 (MCMXXXIII) was a common year starting on Sunday of the Gregorian calendar.
Los Angeles
Los Angeles (L.A.), officially the City of Los Angeles, is a city in Southern California, in the United States. There are 3,847,400 people living in the city, and over 18 million people in the L.A. region. The city has an area of . Los Angeles is the city with the second biggest population in the United States after New York, overtaking Chicago in the 1970s. It is also the biggest city of California. Due to being built on a fault line, which runs through the downtown, it is has few skyscrapers and tall structures and is one of the most spread out cities in the world. Greater Los Angeles is home to many of the biggest rock bands in the history of the United States. Los Angeles is surrounded by East Los Angeles, Huntington Park, Maywood, Walnut Park, Commerce, Bell, Glendale, South Pasadena, Monterey Park, South Gate, Cudahy, West Hollywood, Alhambra, Bell Gardena and Westmont.
Los Angeles has Spanish and Mexican influences due to being a former colony of Mexico and Spain. Los Angeles is a diverse city with many ethnic groups such as Mexican, Japanese, Korean, Vietnamese, Salvadoran, Iranian and Armenian. Mexican and Spanish architecture can be seen in Los Angeles.
Many celebrities live in Los Angeles. Los Angeles is known to be the entertainment capital of the world. Many movies, television shows and fashion shows are set in Los Angeles.
The area comprising present-day Los Angeles County was first settled by small groups of Native Americans for centuries before the first European contact in 1769 when Gaspar de Portola and a group of missionaries camped on what is now the banks of the Los Angeles River. The name Los Angeles comes from the Spanish language,and it means "The Angels". The name is an abbreviation from the original name of the place. The original name is "El Pueblo de Nuestra Señora la Reina de los Ángeles del Río Porciúncula" (in English, "town of our lady the Queen of Angels of the River Porciúncula"), giving it both one of the longest and shortest (referring to its shortening of "LA") place names in the world. Los Angeles was founded in 1781 while the area was within the borders of the Viceroyalty of New Spain. The area had earlier been explored by two Franciscan priests named Junipero Serra and Juan Crespi and following the Mexican War of Independence the region passed into the hands of Mexico which subsequently ceded control of California to the U.S. in 1848. On April 4, 1850 California became a State of the USA. Los Angeles began half a century of rapid growth after railroads arrived in the city in the 1870s. Los Angeles was home to the Olympic Games in 1932 and 1984. It will host the Olympic Games in 2028. Three times the city broke out in riots, in 1943, in 1965, and in 1992, all due to racism. In 1994, an earthquake killed 72 people and damaged many buildings.
Los Angeles is a very large city, and the edges of the city are very far from the center, going from the beaches to the mountains. The Santa Monica Mountains run through the city, separating it into the San Fernando Valley to the north and the Los Angeles Basin to the south. The Los Angeles River also runs through the city some . Los Angeles moves about one-quarter of an inch (6.3 millimeters) to the east every year. It is caused by the city's tectonic plates and rough ground geography and since Los Angeles is at a close distance with the San Andreas Fault. This brings Los Angeles and San Francisco 2.5 inches closer together each year.
The climate in Los Angeles is a Mediterranean climate. The weather is usually warm and dry during the summer, and it is mild and more rainy in the winter. The weather is different depending on how far away from the ocean you are, so places near the beach usually do not get as hot in the summer. It is very rare for temperatures to go below freezing. The city receives about 15 inches (386 mm) of rain each year, although the amount can change a lot from year to year.
L.A. has many famous sights. There are many very long beaches, such as Venice Beach. Many visitors go to Hollywood, home to the Hollywood Walk of Fame the Mann's (Grauman's) Chinese Theater, a large cinema and L.A. Live, an entertainment complex. Los Angeles also has many fine museums such as the L.A. County Museum of Art, California Science Center and the Getty Museum. Another sight is the Los Angeles City Zoo. Los Angeles is the only major city in the world with an active population of wild mountain lions.
Los Angeles is known for its large movie and television industry. Much of this is located in Hollywood. Some military aircraft are also made there, as well as spacecraft. The music industry is also concentrated in the area. The city is also a banking center. The San Pedro area has a busy port.
Los Angeles has dozens of neighborhoods and named areas, including:
As of December 2019, the mayor of Los Angeles is Eric Garcetti.
Los Angeles has a rich history and culture of popular music. Many of the most notable recording artists in the history of the United States either started or flourished in Los Angeles or Greater Los Angeles. The surf music scene is largely associated with Los Angeles and suburbs like Malibu. Motown Records moved from Detroit, Michigan to Los Angeles in the 1970s. The West Coast Hip-hop scene and genres such as G-funk are largely centered in Greater Los Angeles.
Notable bands include:
KCBS CBS
KABC American Broadcasting Company
KTLA The CW
KTTV Fox Broadcasting Company
KCOP My13
Most people who live in Los Angeles are of Mexican American ancestry. Many Armenians, Chinese, Filipinos, Iranians, Salvadorans and Jews live in Los Angeles.
Census
A census is a way of getting information about every member of a population. It is usually used for a population of people, but can be used to mean a population of animals.
Both the United States and United Kingdom have a census every 10 years, or decade. But in Australia, Canada, Japan and New Zealand they have it every 5 years.
A census produces a large database and sometimes new information technology, such as the use of punched cards for data, has been invented to handle it.
The word comes from the Roman Republic when it meant a list of citizens.
Star
A star is a very large ball of bright glowing hot matter in space. That matter is called plasma. Stars are held together by gravity. They give out heat and light because they are very hot.
The amount of material in a star (its mass) is so huge that it starts a nuclear reaction going. The reaction changes hydrogen to helium and gives off heat.