Problem: Frederic Chopin:

Works published since 1857 have received alternative catalogue designations instead of opus numbers. The present standard musicological reference for Chopin's works is the Kobylanska Catalogue (usually represented by the initials 'KK'), named for its compiler, the Polish musicologist Krystyna Kobylanska.

What is the current musicologist reference for Chopin's pieces?
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A: the Kobylanska Catalogue

Problem: Separation of powers under the United States Constitution:

Congress has the sole power to legislate for the United States. Under the nondelegation doctrine, Congress may not delegate its lawmaking responsibilities to any other agency. In this vein, the Supreme Court held in the 1998 case Clinton v. City of New York that Congress could not delegate a "line-item veto" to the President, by powers vested in the government by the Constitution.

In which year was the court case Clinton v. Supreme Court held?
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A: unanswerable

Problem: Karl Popper:

In 1928, he earned a doctorate in psychology, under the supervision of Karl Buhler. His dissertation was entitled "Die Methodenfrage der Denkpsychologie" (The question of method in cognitive psychology). In 1929, he obtained the authorisation to teach mathematics and physics in secondary school, which he started doing. He married his colleague Josefine Anna Henninger (19061985) in 1930. Fearing the rise of Nazism and the threat of the Anschluss, he started to use the evenings and the nights to write his first book Die beiden Grundprobleme der Erkenntnistheorie (The Two Fundamental Problems of the Theory of Knowledge). He needed to publish one to get some academic position in a country that was safe for people of Jewish descent. However, he ended up not publishing the two-volume work, but a condensed version of it with some new material, Logik der Forschung (The Logic of Scientific Discovery), in 1934. Here, he criticised psychologism, naturalism, inductionism, and logical positivism, and put forth his theory of potential falsifiability as the criterion demarcating science from non-science. In 1935 and 1936, he took unpaid leave to go to the United Kingdom for a study visit.

What subjects was Popper authorized to teach in secondary school in 1929?
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A: mathematics and physics

Problem: Database:

The conceptual view provides a level of indirection between internal and external. On one hand it provides a common view of the database, independent of different external view structures, and on the other hand it abstracts away details of how the data are stored or managed (internal level). In principle every level, and even every external view, can be presented by a different data model. In practice usually a given DBMS uses the same data model for both the external and the conceptual levels (e.g., relational model). The internal level, which is hidden inside the DBMS and depends on its implementation, requires a different level of detail and uses its own types of data structure types.

What view can't be presented by a different data model?
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A:
unanswerable