Problem: Russian border troops were stationed along the TajikAfghan border until summer 2005. Since the September 11, 2001 attacks, French troops have been stationed at the Dushanbe Airport in support of air operations of NATO's International Security Assistance Force in Afghanistan. United States Army and Marine Corps personnel periodically visit Tajikistan to conduct joint training missions of up to several weeks duration. The Government of India rebuilt the Ayni Air Base, a military airport located 15 km southwest of Dushanbe, at a cost of $70 million, completing the repairs in September 2010. It is now the main base of the Tajikistan air force. There have been talks with Russia concerning use of the Ayni facility, and Russia continues to maintain a large base on the outskirts of Dushanbe.
Why do US troops visit Tajikistan every so often?
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Answer: to conduct joint training missions of up to several weeks duration.

Problem: The Netherlands regained independence from France in 1813. In the Anglo-Dutch Treaty of 1814 the names "United Provinces of the Netherlands" and "United Netherlands" were used. In 1815 it was rejoined with the Austrian Netherlands, Luxembourg and Liege (the "Southern provinces") to become the Kingdom of the Netherlands, informally known as the Kingdom of the United Netherlands, to create a strong buffer state north of France. After Belgium and Luxembourg became independent, the state became unequivocally known as the Kingdom of the Netherlands, as it remains today.
What happened to the Kingdom of the United Netherlands after France became independent?
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Answer: unanswerable

Problem: Data compression can be viewed as a special case of data differencing: Data differencing consists of producing a difference given a source and a target, with patching producing a target given a source and a difference, while data compression consists of producing a compressed file given a target, and decompression consists of producing a target given only a compressed file. Thus, one can consider data compression as data differencing with empty source data, the compressed file corresponding to a "difference from nothing." This is the same as considering absolute entropy (corresponding to data compression) as a special case of relative entropy (corresponding to data differencing) with no initial data.
What can be looked at as a special case of data differencing?
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Answer:
Data compression