Some books are written just for children, or for entertainment, while other books are for studying something in school such as math or history. Many books have photographs or drawings.
There are two main kinds of book text: fiction and non-fiction.
These books are novels, about stories that did not happen, and have been imagined by the author. Some books are based on real events from history, but the author has created imaginary characters or dialogue for the events.
Books of non-fiction are about true facts or things that have really happened. Some examples are dictionaries, cookbooks, textbooks for learning in school, or a biography (someone's life story).
Between the written manuscript and the book lie several inventions. Manuscripts are hand-made, but books are now industrial products.
A common type of manuscript was the scroll, which was a long sheet rolled up. The sheet could have been made of papyrus (made by the Egyptians, by weaving the inner stems of the papyrus plant and then hammering them together), or parchment or vellum (very thin animal skin, first used by the ancient Greeks), or paper (made from plant fibers, invented by the Chinese). Manuscripts of this kind lasted to the 16th century and beyond. Turning the manuscript into a book required several developments.
The Romans were the first people to put separate pieces of manuscript between covers, to form a "codex". This was more convenient to handle and store than scrolls, but was not yet a book as we understand it.
Scrolls and codices were written and copied by hand. The Chinese invented "woodblock printing", where shapes are carved out of a block of wood, then ink is applied to the carved side, and the block is pressed onto paper. This woodcut method was slow because the symbols and pictures were made by cutting away the surrounding wood.
Johannes Gutenberg was the first to invent a machine for printing, the printing press, in the 15th century. This involved more than just a press, it involved the production of movable metal type suitable for the machine process.
Initially, the machines were slow, and needed a printer's muscle to make them work. The Industrial Revolution brought steam power and later electrification.
Paper had been invented in China in the 8th century, but it was kept secret for a long time. In Europe hand-made paper was available from about 1450. It was cheaper than parchment but still expensive, and the early printing was a slow process. Therefore, books remained rare. In 1800 the first machines for making paper from wood pulp were invented. New kinds of inks were also invented for various purposes, and machines were driven by steam engines and later by electricity.
The common cheap supply of paper fed the faster printing machines, and books became cheaper. At the same time, in America, Britain and continental Europe, more people learnt to read. So, in the 19th century, many ordinary people could afford to buy books and could actually read them. Also in the 19th century came public libraries, so poorer people could get access to the best books.
Printing was done on large sheets of paper, which were then folded, guillotined (cut) and sewn into the covers. Bookbinding and all the other processes have been done by machines since the 19th century.
Today some of the technologies have been changed, especially those involving illustration and typography. However, books look much the same as they did, with more illustration in colour, but basically the same. That is because experience has shown that readers need certain things for pleasurable reading. Graphic design and typography are the practical arts used to make books attractive and useful to readers.
Sundial
A sundial shows the current solar time during the day. It does this because the sun appears to move through the sky. At different times in the day when the sun is shining, a shadow is cast in different places on the dial. A person marks the dial with the time at a certain shadow. This lets users easily see the time. There are a few commonly seen designs, such as the 'ordinary' or standard horizontal garden sundial. However, sundials can be designed for any surface where a fixed object casts a predictable shadow. They may be horizontal or vertical or tilted.
Ancient Egypt had sundials. Other cultures developed them further, including the Greeks and Romans.
Peninsula
A peninsula is a region of land that sticks out in a body of water. It is also defined as a piece of land with water on three sides.
Many countries are on peninsulas, and may either take up part of a peninsula (such as Portugal) or all of it (such as India). Parts of a country may also be on a peninsula. For example, Jutland is a peninsula, as is Baja California in Mexico.
If Eurasia is considered a continent then the continent of Europe is technically a peninsula. In this case, the great peninsulas of Europe, the Iberian, Italian, and Balkan peninsulas would technically be peninsulas within peninsulas. The area of the European Peninsula, comprised of Europe minus Russia, Fennoscandia, and any islands, is roughly 4.4 million square kilometers.
The Arabian Peninsula is usually cited as the largest peninsula in the world with an area of 3,237,500 square kilometers.
Derivative
A derivative is something created from a Primary source, and can mean different things.
Combinatorial game theory
Combinatorial game theory, also known as CGT is a branch of applied mathematics and theoretical computer science that studies combinatorial games, and is distinct from "traditional" or "economic" game theory. CGT arose in relation to the theory of impartial games, the two-player game of Nim in particular, with an emphasis on "solving" certain types of combinatorial games.
A game must meet several conditions to be a combinatorial game. These are:
Combinatorial Game Theory is largely confined to the study of a subset of combinatorial games which are two player, finite, and have a winner and loser (i.e. do not end in draws.)
These combinatorial games can be represented by trees, each vertex of which is the game resulting from a particular move from the game directly below it on the tree. These games can be assigned game values. Finding these game values is of great interests to CG theorists, as is the theoretical concept of game addition. The sum of two games is the game in which each player on her/his turn must move in only one of the two games, leaving the other as it was.
Elwyn Berlekamp, John Conway and Richard Guy are the founders of the theory. They worked together in the 1960s. Their published work was called "Winning Ways for Your Mathematical Plays".
In the theory, there are two players called "left" and "right". A game is something that allows left and right to make moves to "other games". For example, in the game of chess, there is a usual starting setup. One could also, however, think of a chess game after the first move as a different game, with a different setup. So each position is also called a game.
Games have the notation {L|R}. formula_1 are the games the left player can move to. formula_2 are the games the right player can move to. If you know chess notation, then the usual chess setup is the game
The dots "..." mean there are many moves, so not all are shown.
Chess is very complex. It is better to think of easier games. Nim, for example, is much simpler to think about. Nim is played like this:
The easiest game of Nim starts with no counters at all! In such a case, neither player can move. That is shown as , or 0). If instead right moves first, there will be no more moves for left. So both left and right can make a move to 0. That is shown as <nowiki>, or {0|0}</nowiki>. The first player to move will win. Games equal to {0|0} are very important. They are written with the symbol, * (star).
Nim
Nim is a simple game used for examples in combinatorial game theory. The rules of nim are simple: