question: Riviera Holdings Corporation owned a casino In Nevada which operated until what year?
answer: 2015
context: Title: Riviera (hotel and casino)
  Passage: Riviera (colloquially, "the Riv") was a hotel and casino on the Las Vegas Strip in Winchester, Nevada, which operated from April 1955 to May 2015.  It was last owned by the Las Vegas Convention and Visitors Authority, which decided to demolish it to make way for the Las Vegas Global Business District.
  Title: MiTAC Holdings
  Passage: MiTAC Holdings Corporation, through its subsidiaries (MiTAC International Corp.  and MiTAC Computing Technology),provides GPS navigation devices, automotive solution, cloud services and cloud computing products worldwide.The company offers a range of electronics manufacturing services, such as research and development, design, manufacturing, assembly, marketing, and solutions.It also distributes portable car navigation products, outdoor handheld navigation devices, and mobile GPS solutions; and DashCam for vehicles, portable navigation devices for 4WD, and trucks under the Magellan, Mio, and Navman brand names.In addition, the company designs, manufactures, and markets x86 server/workstation platforms to OEMs, VARs, system integrators, and resellers under the TYAN brand name.  Further, it offers storage products, cloud computing applications, all-in-one PC, thin client, and POS system, as well as smart wearable device and professional tablet series.  MiTAC Holdings Corporation is based in Taipei, Taiwan.
  Title: ABS-CBN Philharmonic Orchestra
  Passage: The ABS-CBN Philharmonic Orchestra is a Philippine broadcast orchestra based in Manila and is operated by ABS-CBN.  The orchestra was founded in 2012, Gerard Salonga served as the orchestra's conductor and musical director.  It is a joint venture of ABS-CBN and First Philippine Holdings Corporation, both under the portfolio of Lopez Holdings Corporation.  The orchestra consists of 40 instrumentalists.  Famous Filipino composer and conductor Ryan Cayabyab lauds the orchestra for its smooth and beautiful music.
  Title: Lopez Group of Companies
  Passage: López Holdings Corporation (formerly Benpres Holdings Corporation) is a Filipino business conglomerate founded by the brothers Eugenio López, Sr. and Fernando López.  It is a major player in the public service and utilities sector in the Philippines and serves as the López family's publicly listed holding company for investments in major development sectors such as broadcasting and cable; telecommunications; power generation and distribution; manufacturing; and property development.  It added to its portfolio investments in other basic service sectors but has also since sold its interest in banking, toll roads, information technology, and health care delivery.
  Title: Riviera Holdings
  Passage: Riviera Holdings Corporation is a defunct casino operator that was based in Winchester, Nevada.  It owned two casinos: the Riviera on the Las Vegas Strip, closed in 2015; and the Riviera Black Hawk in Black Hawk, Colorado, sold in 2011.
citations: Riviera (hotel and casino) Riviera Holdings