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The class of decision problems solvable by a Turing machine. Often identified with the class of 'effectively computable' functions (the Church-Turing thesis).
[[Image:ArmandBombardierStamp.jpg|framed|Right|A Canadian 46¢ stamp, showing Bombardier and his prototype snowmobile.]]
'''Joseph-Armand Bombardier''' ([[April 16]], [[1907]] - [[February 18]], [[1964]]) was a [[Canada|Canadian]] inventor and businessman, who invented the [[snowmobile]] and was the founder of [[Bombardier]]. He made his first snowmobile prototype when he was 15 years old.
Since we can decide any problem for which there exists a recogniser and also a co-recogniser, the class is equal to <math>RE \cap coRE</math>.
He was born into a large family of prosperous farmers and small shopkeepers in the small town of [[Valcourt, Quebec|Valcourt]], not too far from [[Sherbrooke, Quebec|Sherbrooke]], southeast of [[Montreal]] in the province of [[Quebec]]. His brothers were later to help him out in several aspects of running what would eventually become a large [[mechanical engineering]] concern, leaving him free to concentrate on mechanical innovations and high-level corporate orientations. Later still, his own sons and daughters were to be instrumental in making his company grow to international proportions.
==External links==
He started off small by opening a garage in Valcourt in [[1926]], fixing cars and selling [[gasoline]] in the three snow-free seasons of the year, and tinkering with his project of building a snowmobile during the snowbound winter. Before [[World War II]] and on through much of the [[1940s]] the [[Quebec government]] did not plough the rural roads around Valcourt and elsewhere in the province. The inhabitants had to put away their cars and light trucks and resort to horse-drawn sleighs when heavy trucks were not available. The heavy [[snow]] made things difficult for [[general practitioner|family doctors]] or just about anybody who had urgent business to do in these areas, and Joseph-Armand Bombardier saw this as a challenge.
* [http://qwiki.caltech.edu/wiki/Complexity_Zoo#re Complexity Zoo]
[[Category: BombardierComplexity classes]] ▼Bombardier was largely self-taught, picking up [[mechanical engineering]] by fixing things, reading, and taking notes. He had a mechanical genius and a driving ambition to make the winter months as easy to navigate as the other ones. The first snowmobile of his teenage years was a small surface-skimming contraption with a propeller.
{{ComplexityClasses}}
In [[1937]], after years of research and development he started producing the B-7, an enclosed [[half-track]] machine with his [[patent]]ed [[caterpillar track]] and [[sprocket]] assembly in the back and skis in the front. Previous track systems were not suitable for the moist-snow conditions of Southern Quebec.
In [[1942]] he incorporated his company and produced the B-12 machine, which could hold 12 passengers snugly and featured many improvements. The production of the B-12 went on for several decades and examples of it were still found running at the turn of the millennium in remote snowbound areas all over [[North America]].
The decision of the Quebec government to plough country roads in the winter of [[1949]] cost Bombardier much of its local market for the B-12 and its variants. This led Joseph-Armand Bombardier to diversify into other off-terrain tracked vehicles, such as a heavy-duty [[Muskeg]] tractor meant for [[mining]] exploration and the [[forestry]] industries.
Dissatisfaction with suppliers of [[rubber]] track for the big Muskeg tractor led him to make his own, in a subsidiary operated by his son Germain. This in turn made it possible for him to produce a relatively small continuous rubber track for the light one- or two-person snowmobile he had dreamt of as a teenager. When small, reliable [[two-stroke engine]]s appeared in the [[1950s]] he had all the ingredients he needed in hand. He produced the first prototype of the snowmobile in [[1958]] and started production in 1959. Sales were slow in the first years since the mass consumer market was very different from his usual industrial and commercial customer base. When he died in 1964, snowmobiles had gone from sales of 200 a year to 8200, spurring several factory expansions.
In [[2000]], Joseph-Armand Bombardier was honoured by the [[government of Canada]] with his image on a [[List of people on stamps of Canada|postage stamp]].
==Resource==
*[http://www.fjab.qc.ca/ Musée Joseph-Armand Bombardier]
[[Category:1907 births|Bombardier, Joseph-Armand]]
[[Category:1964 deaths|Bombardier, Joseph-Armand]]
[[Category:Canadian businesspeople|Bombardier, Joseph-Armand]]
[[Category:Canadian inventors|Bombardier, Joseph-Armand]]
[[fr:Joseph-Armand Bombardier]]
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