Question: Near what river was German and Canadian professional poker player born?

full_context: Document 1: Nyon: Nyon ] is a municipality in the district of Nyon in the canton of Vaud in Switzerland. It is located some 25 kilometers north east of Geneva's city centre, and since the 1970s it has become part of the Geneva metropolitan area. It lies on the shores of Lake Geneva and is the seat of the district of Nyon. The town has (as of December 2016 ) a population of . It is connected to the rest of Switzerland by way of the Route Suisse, the A1 Motorway and the railways of the "Arc Lémanique".
Document 2: Altstätten: Altstätten is a small historic rural town and a municipality in the district Rhine Valley, in the canton of St. Gall in Switzerland. It is located with some secure distance of about 5 km west from the Alpine Rhine in the flat and wide St. Gall Rhine Valley, which also designates the border with Austria. It further gives access to the higher situated Appenzell to the west.
Document 3: Thomas Müller: Thomas Müller (] ; born 13 September 1989) is a German professional footballer who plays for and vice-captains Bayern Munich and the German national team. A versatile player, Müller plays as a midfielder or forward, and has been deployed in a variety of attacking roles – as an attacking midfielder, second striker, centre forward and on either wing. He has been praised for his positioning, teamwork and stamina, work-rate, and has shown consistency in both scoring and creating goals.
Document 4: Schaffhausen: Schaffhausen (] ; Alemannic German: "Schafuuse" ; French: "Schaffhouse" ; Italian: "Sciaffusa" ; Romansh: "Schaffusa" ; English: Shaffhouse ) is a town with historic roots, a municipality in northern Switzerland, and the capital of the canton of the same name; it has an estimated population of 36,000 as of December 2016 . It is located right next to the shore of the High Rhine; it is one of four Swiss towns – besides Neuhausen a. Rhf., the historic Neunkirch and Stein a. Rh. – that is located on the northern side of the Rhine.
Document 5: Stefan Müller (footballer, born 1974): Stefan Müller (born 8 March 1974 in Schopfheim) is a retired German footballer. He spent his entire career with SC Freiburg, joining the club in 1993, and making his debut the following season as the club went on to finish third in the Bundesliga. He played a further ten seasons for the club, eight of which were at the highest level – Freiburg were relegated in 1997 and 2002, but bounced back immediately on both occasions. In total he made 203 league appearances for the club, scoring 12 times before retiring in 2005. He won five caps for German under-21 team in the mid-1990s.
Document 6: Davos: Davos (German pronunciation ] , rarely ] ,; Romansh: "" , archaic Italian: "Tavate") is a Alpine town, and a municipality in the Prättigau/Davos Region in the canton of Graubünden, Switzerland. It has a permanent population of (2016 ). Davos is located on the river Landwasser, in the Rhaetian Alps, between the Plessur and Albula Range. At 1560 m , it is the highest "town" in Europe.
Document 7: Daniel Negreanu: Daniel Negreanu ( ; born July 26, 1974) is a Canadian professional poker player who has won six World Series of Poker (WSOP) bracelets and two World Poker Tour (WPT) championship titles. The independent poker ranking service Global Poker Index (GPI) recognised Negreanu as the best poker player of the decade in 2014.
Document 8: SV Schaffhausen: SV Schaffhausen is a Swiss football club based in Schaffhausen, in the north of the country. It was founded in 1922. The club colors are black and white. The club nickname is "Spielvi." The club operates a total of twenty teams, including 4 men's teams and 16 junior teams. They are known to be more active within local football than their bigger local rivals FC Schaffhausen. They currently play in the Swiss 1. Liga, the third tier of Swiss football.
Document 9: Lausanne: Lausanne ( , ] , German: "Lausanne" , and also "Lausannen" Italian: "Losanna" , Romansh: "Losanna" ) is a city in the French-speaking part of Switzerland, and the capital and biggest city of the canton of Vaud. The city is situated on the shores of Lake Geneva (French: "Lac Léman" , or simply "Le Léman"). It faces the French town of Évian-les-Bains, with the Jura Mountains to its north-west. Lausanne is located 62 km northeast of Geneva.
Document 10: Chur: Chur or Coire (] or ] ; Romansh: "Cuira" ] or ] ; Italian: "Coira" ] ; French: "Coire" ] ) is the capital and largest town of the Swiss canton of Grisons and lies in the Grisonian Rhine Valley, where the Rhine turns towards the north, in the northern part of the canton. The city, which is located on the right bank of the Rhine, is reputedly the oldest town of Switzerland.
Document 11: Greg Mueller: Greg Mueller (born 2 June 1971) is a German and Canadian professional poker player and former professional ice hockey defenceman. Mueller was born in Schaffhausen, Switzerland.
Document 12: Lucien Muller: Lucien Muller-Schmidt (born September 3, 1934) is a former French footballer and manager born in Bischwiller who played as a midfielder.
Document 13: Jeff Mueller: Jeff Mueller is an American vocalist and guitarist best known as a member of the math rock bands Rodan, Shipping News and June of 44. His bands have been critically recognized for being key forerunners in the development of post-rock, math rock and post-hardcore. His only solo, titled "Fold and Perish", was released in 1999 by Monitor Records. He currently lives in New Haven, Connecticut.
Document 14: Ross Muir: Ross Muir (born 6 October 1995 in Edinburgh) is a Scottish professional snooker player. He is noted for being the only professional snooker player who regularly wears a glove on the bridge hand, Muir turned professional in 2013 after graduating from event two of the Q School, defeating David Morris 4–0 in the final round.
Document 15: Sven Müller (racing driver): Sven Müller (born February 7, 1992 in Mainz) is a German racing driver currently racing for Porsche Motorsport as a factory driver. He is the reigning Porsche Supercup champion during 2017.
ground_truth: Rhine