question: Who reigned for 50 months as lineal champion  and fought Richard Williams?
answer: Sergio Gabriel Martínez
context: Title: Mike Tyson vs. Michael Spinks
  Passage: Mike Tyson vs. Michael Spinks was a boxing match which took place on Monday June 27, 1988.  Both men were undefeated and each had a claim to being the legitimate heavyweight champion.  At the time, Tyson held the belts of all three of the major sanctioning organizations (World Boxing Council, World Boxing Association, and International Boxing Federation) while Spinks was the "Ring" champion and was considered the lineal champion.
  Title: Dover Christ Church Academy
  Passage: The Dover Christ Church Academy opened in September 2010 when it replaced Archers Court Maths and Computing College which had been placed in the National Challenge.  Dover Christ Church was backed by the Dover Grammar schools, Canterbury Christ Church University as well as the Local Education Authority (Kent).  Richard Williams was the first principal to be at the school, joining the school at the start of its era from Medina High School on the Isle of Wight.  Richard Williams left the school in 2013 Samantha Williamson took over the role of principal, temporarily at first, then on a permanent basis in 2014.
  Title: Ernest Moore (professor)
  Passage: Ernest Moore is a former aide to US Congressman Danny Davis and a former visiting assistant professor at Williams College.  Moore used the pseudonym Ernest Moore while teaching at Williams.  On September 23, 2010, Moore was sentenced to 50 months in prison and ordered to pay $760,000 for various financial frauds.  Moore originally pleaded guilty in November 2009.
  Title: Sergio Martínez (boxer)
  Passage: Sergio Gabriel Martínez (born February 21, 1975) is an Argentine former professional boxer who competed from 1997 to 2014.  He held the unified WBC, WBO, "Ring" magazine, and lineal middleweight titles between 2010 and 2014, making six successful defenses of the latter two titles.  Martínez's 50-month reign as lineal champion ranks as one of the longest in middleweight history.  He also fought at light middleweight, where he held the IBO title from 2003 to 2005, and the WBC interim title in 2008 (later elevated to full world champion status the following year).
  Title: Lineal championship
  Passage: In combat sports where champions are decided by a challenge, the lineal championship of a weight class is a world championship title held initially by an undisputed champion and subsequently by a fighter who defeats the reigning champion in a match at that weight class.  In professional boxing, the lineal champion is informally called "the man who beat the man".  Champions recognized by sanctioning bodies such as the World Boxing Association (WBA) or World Boxing Council (WBC), or the Ultimate Fighting Championship (UFC) may vacate their title voluntarily, or be stripped of the title for breaching the sanctioning body's regulations or contracts.  There will thus be a breach of continuity in the list of sanctioned champions which the lineal championship is intended to prevent.  However, there is no single canonical list of lineal champions at any weight class, because there is no agreed upon method of determining the starting point for each lineage and conflicting opinions on what to do when the current champion retires or moves to a different weight class, although there is agreement that any stripping of a title be discounted.
  Title: Lennox Lewis
  Passage: Lennox Claudius Lewis, {'1': ", '2': ", '3': ", '4': "} , {'1': ", '2': ", '3': ", '4': "} (born 2 September 1965) is a former professional boxer who competed from 1989 to 2003.  He is a three-time world heavyweight champion, a two-time lineal champion, and remains the last heavyweight to hold the undisputed title.  Lewis holds dual British and Canadian citizenship; as an amateur he represented Canada at the 1988 Summer Olympics, winning a gold medal in the super-heavyweight division after defeating future world champion Riddick Bowe in the final.
  Title: Emery Hawkins
  Passage: Emery Hawkins (April 30, 1912 – June 1989) was an American animator who worked at various studios such as Disney, Screen Gems, Walter Lantz, Warner Bros., MGM, and UPA during the golden age of animation.  His most prominent work is the Woody Woodpecker cartoons from the 1940s.  Along with Art Heinemann, Hawkins helped redesign Woody and made him more streamlined.  He also worked with Art Babbitt and Ken Harris on Richard Williams's unfinished animated feature The Thief and the Cobbler.  Hawkins was known for the speed in which he animated, completing scenes quickly, but with perfection.  Hawkins (along with Babbitt, Harris and Grim Natwick) is frequently mentioned in Richard Williams' book "The Animator's Survival Kit".
  Title: Richard Williams (basketball coach)
  Passage: Richard Williams was the college basketball head coach at Mississippi State from 1986 to 1998.  He is the 2nd most successful coach in school history with 191 victories (191–163 .540) bested only by his former assistant, Rick Stansbury.  His 1991 squad won the Southeastern Conference championship and made the NCAA tournament losing in the first round to Eastern Michigan.  His 1995 squad made the Sweet Sixteen, and his 1996 squad made the school's only Final Four appearance losing to Syracuse 77–69.  He received two SEC Coach of the Year awards.  Richard Williams resigned as the head coach at MSU two years removed from his Final Four appearance.  After leaving MSU, he coached the Memphis Houn'Dawgs of the ABA and the Jackson Rage of the WBA.  and coached for a time at his alma mater, Pearl High School.  He served as the Director of Basketball Administration at UAB in 2008 and in 2009 he was named the Director of Basketball Administration and Program Coordinator for the Louisiana Tech men’s basketball team on a volunteer basis.
  Title: Richard Williams (boxer)
  Passage: Richard "The Secret" Williams ( (1971--) 09 1971 (age (2017)-(1971)-((11)<(05)or(11)==(05)and(30)<(09)) ) is an English professional light middle/middle/super middleweight boxer of the 1990s, 2000s and 2010s who won the International Boxing Organization (IBO) light middleweight title, and Commonwealth light middleweight title (twice), and was a challenger for the International Boxing Organization (IBO) light middleweight title against Sergio Gabriel Martinez, and British Boxing Board of Control (BBBofC) British middleweight title against Howard Eastman, his professional fighting weight varied from 149+3/4 lb , i.e. light middleweight to 162+1/4 lb , i.e. super middleweight.  Richard Williams is trained by Brian Lawrence, and managed by Barry Hearn, and John Rooney.
  Title: Naseem Hamed
  Passage: Naseem Hamed (Arabic: نسيم حميد‎ ‎ ; born 12 February 1974), commonly known as "Prince" Naseem or "Naz", is a British former professional boxer who competed from 1992 to 2002.  He held multiple world championships at featherweight, including the WBO title from 1995 to 2000; the IBF title in 1997; and the WBC title from 1999 to 2000.  He also reigned as lineal champion from 1998 to 2001; IBO champion from 2002 to 2003; and held the European bantamweight title from 1994 to 1995.  Hamed is ranked as the third best British featherweight boxer of all time by BoxRec.  In 2015 he was inducted into the International Boxing Hall of Fame.
citations: Sergio Martínez (boxer) Richard Williams (boxer)