The 17th Century: The Invention of the First "Computers" The devices often considered the first "computers" in our understanding were rather calculators than the sophisticated combination of hard- and software we call computers today. In 1642 Blaise Pascal, the son of a French tax collector, developed a device to perform additions. His numerical wheel calculator was a brass rectangular box and used eight movable dials to add sums up to eight figures long. Designed to help his father with his duties, the big disadvantage of the Pascaline was its limitation to addition. Gottfried Wilhelm von Leibniz, a German mathematician and philosopher, in 1694 improved the Pascaline by creating a machine that could also multiply. As its predecessor Leibniz's mechanical multiplier likewise worked by a system of gears and dials. Leibniz also formulated a model that may be considered the theoretical ancestor of some modern computers. In De Arte Combinatoria (1666) Leibniz argued that all reasoning, all discover, verbal or not, is reducible to an ordered combination of elements, such as numbers, words, colors, or sounds. Further improvements in the field of early computing devices were made by Charles Xavier Thomas de Colmar, a Frenchmen. His arithometer could not only add and multiply, but perform the four basic arithmetic functions and was widely used up until the First World War.

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Expert system Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to artificial intelligence. The three main elements of expert systems are: (1) an interface which allows interaction between the system and the user, (2) a database (also called the knowledge base) which consists of axioms and rules, and (3) the inference engine, a computer program that executes the inference-making process. The disadvantage of rule-based expert systems is that they cannot handle unanticipated events, as every condition that may be encountered must be described by a rule. They also remain limited to narrow problem domains such as troubleshooting malfunctioning equipment or medical image interpretation, but still have the advantage of being much lower in costs compared with paying an expert or a team of specialists.

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