Task: Question Generation
Input (English): Passage: From 1837, Alkan lived in the Square d'Orléans in Paris, which was inhabited by numerous celebrities of the time including Marie Taglioni, Alexandre Dumas, George Sand, and Chopin. Chopin and Alkan were personal friends and often discussed musical topics, including a work on musical theory that Chopin proposed to write. By 1838, at 25 years old, Alkan had reached a peak of his career. He frequently gave recitals, his more mature works had begun to be published, and he often appeared in concerts with Liszt and Chopin. On 23 April 1837 Alkan took part in Liszt's farewell concert in Paris, together with the 14-year-old César Franck and the virtuoso Johann Peter Pixis. On 3 March 1838, at a concert at the piano-maker Pape, Alkan played with Chopin, Zimmerman, and Chopin's pupil Adolphe Gutmann in a performance of Alkan's transcription, now lost, of two movements of Beethoven's Seventh Symphony for two pianos, eight hands.At this point, for a period which coincided with the birth and childhood of his natural son, Élie-Miriam Delaborde (1839–1913), Alkan withdrew into private study and composition for six years, returning to the concert platform only in 1844.  Alkan neither asserted nor denied his paternity of Delaborde, which, however, his contemporaries seemed to assume. Marmontel wrote cryptically in a biography of Delaborde that "[his] birth is a page from a novel in the life of a great artist". Alkan gave early piano lessons to Delaborde, who was to follow his natural father as a keyboard virtuoso.Alkan's return to the concert platform in 1844 was greeted with enthusiasm by critics, who noted the "admirable perfection" of his technique, and lauded him as "a model of science and inspiration", a "sensation" and an "explosion". They also commented on the attending celebrities including Liszt, Chopin, Sand and Dumas. In the same year he published his piano étude Le chemin de fer, which critics, following Ronald Smith, believe to be the first representation in music of a steam engine. Between 1844 and 1848 Alkan produced a series of virtuoso pieces, the 25 Préludes Op. 31 for piano or organ, and the sonata Op. 33 Les quatre âges. Following an Alkan recital in 1848, the composer Giacomo Meyerbeer was so impressed that he invited the pianist, whom he considered "a most remarkable artist", to prepare the piano arrangement of the overture to his forthcoming opera, Le prophète. Meyerbeer heard and approved Alkan's arrangement of the overture for four hands (which Alkan played with his brother Napoléon) in 1849; published in 1850, it is the only record of the overture, which was scrapped during rehearsals at the Opéra.
Output (English): What is the first name of the brother of the man who neither asserted nor denied his paternity of Delaborde?