The first Sonata for viola and piano (German: "Sonate für Bratsche und Klavier" ), also known as "Sonata in F", Op.
 11, No. 4, by Paul Hindemith was composed in 1919.
 It is the fourth of five instrumental sonatas comprising his opus 11.
 This sonata and the following Op. 11 No. 5 for solo viola mark Hindemith's decision to abandon playing the violin in favor of its larger cousin.
The international Paul Hindemith Prize promotes outstanding contemporary composers within the framework of the Schleswig-Holstein Music Festival (SHMF).
 The award commemorates the musical pedagogy of Paul Hindemith, who wrote the composition "Plöner Musiktag" in 1932 on behalf of the Staatliche Bildungsanstalt Plön.
 The music prize is endowed with 20,000 € and goes together with a composition commission.
 The prize is presented annually by the Hindemith Foundation in Blonay (Switzerland), the Walter and Käthe Busche Foundation, the Rudolf and Erika Koch Foundation, the Gerhard Trede Foundation, the Franz Wirth Memorial Trust and the Cultural Office of the Free and Hanseatic City of Hamburg since 1990.
 Since 2010, the winner is found partly by a composition competition.
 The work of the prize winner is to be premiered within the framework of the Schleswig-Holstein Music Festival.
Mörder, Hoffnung der Frauen ("Murderer, Hope of Women") is an opera in one act by Paul Hindemith, written in 1919 on a German libretto by Oskar Kokoschka which he based on his play of 1907.
 The opera was the first in a triptych of expressionist one-act operas, the others being "Das Nusch-Nuschi", and "Sancta Susanna".
 They were the first operas written by Hindemith.
 The first two were premiered together in Stuttgart on 4 June 1921, all three were performed at the Frankfurt Opera in 1922.
The "Konzertmusik" for Brass and String Orchestra, Op. 50, is a work by Paul Hindemith, composed in 1930.
 It was one of a large group of pieces commissioned for the 50th anniversary of the Boston Symphony Orchestra by its music director, Serge Koussevitzky (others include the Piano Concerto in G major by Maurice Ravel, the Symphony of Psalms by Igor Stravinsky, and Aaron Copland's "Symphonic Ode").
 Koussevitzky conducted the premiere of Hindemith's work with the Boston Symphony Orchestra on 3 April 1931.
Edward Purrington (December 6, 1929 – April 14, 2012) was an American opera director and artistic administrator.
 He began his career at the Santa Fe Opera in 1959 working in various positions through 1971, including stage manager, stage director, instructor in the Apprentice Program, business manager, and director of development and public relations.
 He had the fortune of getting to work directly with many fine opera composers during his years with the SFO, such as Igor Stravinsky, Paul Hindemith, Gian Carlo Menotti, and Krzysztof Penderecki.
Paul Hindemith ( ) (16 November 1895 – 28 December 1963) was a prolific German composer, violist, violinist, teacher and conductor.
 Notable compositions include his song cycle "Das Marienleben" (1923), "Der Schwanendreher" for viola and orchestra (1935), and opera "Mathis der Maler" (1938).
 Hindemith's most popular work, both on record and in the concert hall, is likely the "Symphonic Metamorphosis of Themes by Carl Maria von Weber", written in 1943.
Das Marienleben ("The Life of Mary") is a song cycle by German composer Paul Hindemith.
 The cycle, written for piano and soprano, sets to music a collection of 15 poems by Rainer Maria Rilke that tells the story of the life of Mary.
 Thirteen years after its 1923 premiere in Frankfurt, Hindemith began extensively revising and reworking the piece, eventually producing a second version which premiered in Hanover in 1948.
Nobilissima visione ("The Noblest Vision") is a 50-minute ballet (or, more precisely, a "dance legend") in six scenes by Paul Hindemith, originally choreographed by Léonide Massine for the Ballet Russe de Monte Carlo.
 The libretto by Hindemith and Massine depicts episodes from the life of Saint Francis of Assisi.
 The work was completed in February 1938 and premiered at Theatre Royal, Drury Lane in London on 21 July 1938, with sets and costumes by Pavel Tchelitchew and under the baton of the composer.
 He led one performance of the new ballet at the Metropolitan Opera House in New York (for which the title was temporarily altered to "Saint Francis") on 14 October of the same year.
Mathis der Maler ("Matthias the Painter") is an opera by Paul Hindemith.
 The opera's genesis lay in Hindemith's interest in the Reformation.
 The work's protagonist, Matthias Grünewald, was an actual historical figure who flourished in that era, and whose art, in particular the Isenheim Altarpiece, inspired many creative figures in the early 20th century, including Joris-Karl Huysmans's novel "Là-bas".
Symphony: Mathis der Maler ("Matthias the Painter") is among the most famous orchestral works of German composer Paul Hindemith.
 Music from the symphony was incorporated into, or reworked for, Hindemith's opera "Mathis der Maler", which concerns the painter Matthias Grünewald (or Neithardt).

Question: In what style of art did Edward Purrington and Paul Hindemith collaborate?
Answer: opera