Violin Concerto No. 7 (Mozart) to the insertion of new works bearing the numbers K. 271b to K. 271H in the catalogue. He believed that the work was based on a rough sketch of a violin concerto by Mozart from 1777, but states that the original form of the work cannot easily be reconstructed. The uncharacteristic number of passages for the solo violin in the high register, in "pizzicato" (in the second movement), and in double stops in tenths were considered by Einstein to be 19th-century additions. Friedrich Blume, on the other hand, was firmly in favour of the work's authenticity, stating that "not one
19th century in science later in the 19th century by the German mathematician Bernhard Riemann; here no parallel can be found and the angles in a triangle add up to more than 180°. Riemann also developed Riemannian geometry, which unifies and vastly generalizes the three types of geometry. The 19th century saw the beginning of a great deal of abstract algebra. Hermann Grassmann in Germany gave a first version of vector spaces, William Rowan Hamilton in Ireland developed noncommutative algebra. The British mathematician George Boole devised an algebra that soon evolved into what is now called Boolean algebra, in which the only numbers were