Question: Barbara Jordan and Mark Knowles are both what?

full_context: Document 1: Billie Jean King: Billie Jean King ("née" Moffitt; born November 22, 1943) is an American former World No. 1 professional tennis player. King won 39 Grand Slam titles: 12 in singles, 16 in women's doubles, and 11 in mixed doubles. King won the singles title at the inaugural WTA Tour Championships. King often represented the United States in the Federation Cup and the Wightman Cup. She was a member of the victorious United States team in seven Federation Cups and nine Wightman Cups. For three years, King was the United States' captain in the Federation Cup.
Document 2: 2002 RCA Championships – Doubles: Mark Knowles and Brian MacPhie were the defending champions but they competed with different partners that year, Knowles with Daniel Nestor and MacPhie with Nenad Zimonjić.
Document 3: 2008 Stella Artois Championships – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Knowles chose not to participate, and only Nestor competed that year.
Document 4: Kathy Jordan: Kathryn "Kathy" Jordan (born December 3, 1959) is a former American tennis player. During her career, she won seven Grand Slam titles, five of them in women's doubles and two in mixed doubles. She also was the 1983 Australian Open women's singles runner-up and won three singles titles and 42 doubles titles.
Document 5: 2013 SAP Open – Doubles: Mark Knowles and Xavier Malisse were the defending champions but Knowles did not participate this year because of his retirement from professional tennis in September 2012.<br>
Document 6: Jennifer Capriati: Jennifer Maria Capriati (born March 29, 1976) is an American former professional tennis player. A member of the International Tennis Hall of Fame, she won three singles championships in Grand Slam tournaments and a gold medal at the 1992 Summer Olympics in Barcelona, reached the World No. 1 ranking, and is considered one of the greatest tennis players of all time.
Document 7: 1983 Australian Open – Women's Singles: First-seeded Martina Navratilova defeated ninth-seeded Kathy Jordan 6–2, 7–6 in the final to win the Women's Singles title at the 1983 Australian Open tennis tournament. The tournament was played on grass courts at the Kooyong Stadium in Melbourne from 29 November through 11 December 1983. Navratilova earned $75,000 prize money for winning the title, her 8th career Grand Slam singles title and her 2nd title at the Australian Open after 1981. She improved her year record to 86 wins and 1 loss. This tournament was also notable for being the first Australian Open in which Steffi Graf appeared in the main draw, and the last time that Billie Jean King appeared in the main singles draw of a grand slam.
Document 8: 2008 French Open – Men's Doubles: Mark Knowles and Daniel Nestor were the defending champions, but did not compete together. Knowles partnered with Mahesh Bhupathi, but lost in the first round to Stephen Huss and Ross Hutchins.
Document 9: Barbara Jordan (tennis): Barbara Jordan (born April 2, 1957) is a former professional female tennis player from the United States who won the 1979 Australian Open singles title.
Document 10: Tracy Austin: Tracy Ann Austin Holt (born December 12, 1962) is an American former World No. 1 retired professional tennis player. She won three Grand Slam titles, including the women's singles titles at the 1979 and 1981 US Opens, and the mixed doubles title at the Wimbledon Championships in 1980. Additionally, she won the WTA Tour Championships in 1980 and the year-ending Toyota Championships in 1981, both in singles. A series of injuries and a serious automobile accident cut short her career. Since 1979, she has been the youngest US Open female singles champion in history, and she is the youngest inductee of all time at the International Tennis Hall of Fame. Austin won singles titles on all playing surfaces: clay (both red clay and green clay), indoor carpet, grass, and hard courts.
Document 11: 2005 Mutua Madrileña Masters Madrid – Doubles: Mark Knowles and Daniel Nestor were the defending champions and successfully defended their title, defeating Leander Paes and Nenad Zimonjić 3–6, 6–3, 6–2 in the final. It was the 39th doubles title for Knowles and the 41th doubles title for Nestor, in their respective careers. It was also the 4th and final title of the year for the pair.
Document 12: Jane Blalock: Barbara Jane Blalock (born September 19, 1945) is an American business executive and retired professional golfer. After winning several New England golf tournaments in her youth, Blalock joined the LPGA Tour as a professional in 1969, being named LPGA Tour Rookie of the Year in 1969 and Most Improved Golfer in 1970 and 1971. She won the historically notable Dinah Shore Colgate Winner's Circle in 1972, earning "the richest prize in women's golf history." After successfully fighting a suspension from the LPGA for allegedly signing an incorrect scorecard a month after Dinah Shore, by 1977 she was the sixth-highest paid female golfer of all time. "The Evening Independent" described her as "one of the foremost women golfers of her time" the following year. Nursing a herniated disc, Blalock failed to win a tournament from 1981 until 1984, though after two wins in 1985 she was named Comeback Player of the Year by "Golf Digest".
Document 13: 2007 Davidoff Swiss Indoors – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Nestor chose not to participate, and only Knowles competed that year.
Document 14: Mark Knowles: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis. He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor. At various times between 2002 and 2005 he was ranked World No. 1 in doubles. He is a five-time Olympian.
Document 15: Daniel Nestor: Daniel Mark Nestor {'1': ", '2': ", '3': ", '4': "} (Serbian Cyrillic: Данијел Несторовић; born September 4, 1972 as Danijel Nestorović) is a Canadian professional tennis player. He is one of the foremost doubles players in tennis history due to his longevity and continued success at the top of the men's game. s of 2016 , he is 11th for most men's ATP titles in Open Era history. In January 2016, Nestor became the first doubles player in ATP history to win 1000 matches.
ground_truth: former tennis player