The problem: Answer a question about this article:
Sub- and quotient groups are related in the following way: a subset H of G can be seen as an injective map H G, i.e. any element of the target has at most one element that maps to it. The counterpart to injective maps are surjective maps (every element of the target is mapped onto), such as the canonical map G G / N.y["] Interpreting subgroup and quotients in light of these homomorphisms emphasizes the structural concept inherent to these definitions alluded to in the introduction. In general, homomorphisms are neither injective nor surjective. Kernel and image of group homomorphisms and the first isomorphism theorem address this phenomenon.
What theory address the phenomenon of homomorphisms being neither injective nor surjective?
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The answer: the first isomorphism theorem

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Victoria's youngest son, Leopold, was affected by the blood-clotting disease haemophilia B and two of her five daughters, Alice and Beatrice, were carriers. Royal haemophiliacs descended from Victoria included her great-grandsons, Tsarevich Alexei of Russia, Alfonso, Prince of Asturias, and Infante Gonzalo of Spain. The presence of the disease in Victoria's descendants, but not in her ancestors, led to modern speculation that her true father was not the Duke of Kent but a haemophiliac. There is no documentary evidence of a haemophiliac in connection with Victoria's mother, and as male carriers always suffer the disease, even if such a man had existed he would have been seriously ill. It is more likely that the mutation arose spontaneously because Victoria's father was over 50 at the time of her conception and haemophilia arises more frequently in the children of older fathers. Spontaneous mutations account for about a third of cases.
In how many births do spontaneous cases of haemophilia arise?
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The answer: about a third of cases

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After Napoleon imposed the Convention of Artlenburg (Convention of the Elbe) on July 5, 1803, about 30,000 French soldiers occupied Hanover. The Convention also required disbanding the army of Hanover. However, George III did not recognize the Convention of the Elbe. This resulted in a great number of soldiers from Hanover eventually emigrating to Great Britain, where the King's German Legion was formed. It was the only German army to fight against France throughout the entire Napoleonic wars. The Legion later played an important role in the Battle of Waterloo in 1815. The Congress of Vienna in 1815 elevated the electorate to the Kingdom of Hanover. The capital town Hanover expanded to the western bank of the Leine and since then has grown considerably.
Who elevated Hanover to the Kingdom of Hanover in 1815?
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The answer: The Congress of Vienna

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Human interference has nearly exterminated the trees in many areas, and, except for the beech forests of the Austrian Alps, forests of deciduous trees are rarely found after the extreme deforestation between the 17th and 19th centuries. The vegetation has changed since the second half of the 20th century, as the high alpine meadows cease to be harvested for hay or used for grazing which eventually might result in a regrowth of forest. In some areas the modern practice of building ski runs by mechanical means has destroyed the underlying tundra from which the plant life cannot recover during the non-skiing months, whereas areas that still practice a natural piste type of ski slope building preserve the fragile underlayers.
The practice of building ski runs by mechanical means has destroyed what?
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The answer:
the underlying tundra