Problem: Karl Popper:

While there is some dispute as to the matter of influence, Popper had a long-standing and close friendship with economist Friedrich Hayek, who was also brought to the London School of Economics from Vienna. Each found support and similarities in the other's work, citing each other often, though not without qualification. In a letter to Hayek in 1944, Popper stated, "I think I have learnt more from you than from any other living thinker, except perhaps Alfred Tarski." Popper dedicated his Conjectures and Refutations to Hayek. For his part, Hayek dedicated a collection of papers, Studies in Philosophy, Politics, and Economics, to Popper, and in 1982 said, "...ever since his Logik der Forschung first came out in 1934, I have been a complete adherent to his general theory of methodology."

In which year did Popper write Hayek a letter expressing his intellectual debt to him?
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A: 1944


Problem: Sony Music Entertainment:

In the 1980s to early 1990s, there was a CBS imprint label in the US known as CBS Associated Records. Tony Martell, veteran CBS and Epic Records A&R Vice President was head of this label and signed artists including Ozzy Osbourne, the Fabulous Thunderbirds, Electric Light Orchestra, Joan Jett, and Henry Lee Summer. This label was a part of (Epic/Portrait/Associated) wing of sub labels at CBS which shared the same national and regional staff as the rest of Epic Records and was a part of the full CBS Records worldwide distribution system.

What label was a part of wing of sub labels at ABC?
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A: unanswerable


Problem: Frédéric Chopin:

On 3 December, Chopin complained about his bad health and the incompetence of the doctors in Majorca: "Three doctors have visited me ... The first said I was dead; the second said I was dying; and the third said I was about to die." He also had problems having his Pleyel piano sent to him. It finally arrived from Paris in December. Chopin wrote to Pleyel in January 1839: "I am sending you my Preludes [(Op. 28)]. I finished them on your little piano, which arrived in the best possible condition in spite of the sea, the bad weather and the Palma customs." Chopin was also able to undertake work on his Ballade No. 2, Op. 38; two Polonaises, Op. 40; and the Scherzo No. 3, Op. 39.

Who did Chopin send his Preludes to?
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A: Pleyel


Problem: Vacuum:

QED vacuum has interesting and complex properties. In QED vacuum, the electric and magnetic fields have zero average values, but their variances are not zero. As a result, QED vacuum contains vacuum fluctuations (virtual particles that hop into and out of existence), and a finite energy called vacuum energy. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission and the Lamb shift. Coulomb's law and the electric potential in vacuum near an electric charge are modified.

When are electric and magnetic fields with zero average values, but their variances are not at zero?
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A:
In QED vacuum