- In computability theory, the halting problem is the problem of determining, from a description of an arbitrary computer program and an input, whether the program will finish running, or continue to run forever. The halting problem is undecidable, meaning that no general algorithm exists that solves the halting problem for all possible program–input pairs. The problem comes up often in discussions of computability since it demonstrates that some functions are mathematically definable but not computable.
- Andorra (Wikipedia)
Andorra, officially the Principality of Andorra, is a sovereign landlocked country on the Iberian Peninsula, in the eastern Pyrenees, bordered by France to the north and Spain to the south. Believed to have been created by Charlemagne, Andorra was ruled by the count of Urgell until 988, when it was transferred to the Roman Catholic Diocese of Urgell. The present principality was formed by a charter in 1278. It is currently headed by two co-princes: the bishop of Urgell in Catalonia, Spain and the president of France. Its capital and largest city is Andorra la Vella.