Input: Read this: Due to the tree structure of the filter bank, pre-echo problems are made worse, as the combined impulse response of the two filter banks does not, and cannot, provide an optimum solution in time/frequency resolution. Additionally, the combining of the two filter banks' outputs creates aliasing problems that must be handled partially by the "aliasing compensation" stage; however, that creates excess energy to be coded in the frequency domain, thereby decreasing coding efficiency.[citation needed]
Question: Combining two filter banks' outputs creates what kind of problem?

Output: aliasing


Input: Read this: Beginning roughly in the 14th century in Florence, and later spreading through Europe with the development of the printing press, a Renaissance of knowledge challenged traditional doctrines in science and theology, with the Arabic texts and thought bringing about rediscovery of classical Greek and Roman knowledge.
Question: When was the start of the period known as Greek and Roman?

Output: unanswerable


Input: Read this: In 1846, the United States went to war against Mexico and sent a naval and land expedition to conquer Alta California. At first they had an easy time of it capturing the major ports including San Diego, but the Californios in southern Alta California struck back. Following the successful revolt in Los Angeles, the American garrison at San Diego was driven out without firing a shot in early October 1846. Mexican partisans held San Diego for three weeks until October 24, 1846, when the Americans recaptured it. For the next several months the Americans were blockaded inside the pueblo. Skirmishes occurred daily and snipers shot into the town every night. The Californios drove cattle away from the pueblo hoping to starve the Americans and their Californio supporters out. On December 1 the Americans garrison learned that the dragoons of General Stephen W. Kearney were at Warner's Ranch. Commodore Robert F. Stockton sent a mounted force of fifty under Captain Archibald Gillespie to march north to meet him. Their joint command of 150 men, returning to San Diego, encountered about 93 Californios under Andrés Pico. In the ensuing Battle of San Pasqual, fought in the San Pasqual Valley which is now part of the city of San Diego, the Americans suffered their worst losses in the campaign. Subsequently a column led by Lieutenant Gray arrived from San Diego, rescuing Kearny's battered and blockaded command.
Question: How many weeks did Mexican partisans hold San Diego before it was recaptured by Americans?

Output: three weeks


Input: Read this: Regular script has been attributed to Zhong Yao, of the Eastern Han to Cao Wei period (c. 151–230 AD), who has been called the "father of regular script". However, some scholars postulate that one person alone could not have developed a new script which was universally adopted, but could only have been a contributor to its gradual formation. The earliest surviving pieces written in regular script are copies of Yao's works, including at least one copied by Wang Xizhi. This new script, which is the dominant modern Chinese script, developed out of a neatly written form of early semi-cursive, with addition of the pause (頓/顿 dùn) technique to end horizontal strokes, plus heavy tails on strokes which are written to the downward-right diagonal. Thus, early regular script emerged from a neat, formal form of semi-cursive, which had itself emerged from neo-clerical (a simplified, convenient form of clerical script). It then matured further in the Eastern Jin dynasty in the hands of the "Sage of Calligraphy", Wang Xizhi, and his son Wang Xianzhi. It was not, however, in widespread use at that time, and most writers continued using neo-clerical, or a somewhat semi-cursive form of it, for daily writing, while the conservative bafen clerical script remained in use on some stelae, alongside some semi-cursive, but primarily neo-clerical.
Question: Who was the son of Wang Zishi?

Output:
Wang Xianzhi