Problem: Background: The Wallflowers are an American rock band formed in Los Angeles in 1989 by singer-songwriter Jakob Dylan and guitarist Tobi Miller. The band has gone through a number of personnel changes but has remained centered on Dylan. After releasing their eponymous debut album in 1992, the Wallflowers released what would become their best-known and highest-selling album, Bringing Down the Horse in 1996, which featured songs such as "One Headlight" and "6th Avenue Heartache". They went on to release an additional three albums before going on a seven-year hiatus, beginning in 2006.
Context: In July 2004, the Wallflowers returned to the studio to record their fifth album, Rebel, Sweetheart. This time the band decided to record in Atlanta, Georgia, which is where their producer for this album, Brendan O'Brien, is based. O'Brien also contributed on guitar. Fred Eltringham joined the Wallflowers as their new drummer. Jakob Dylan wrote the songs, of which keyboardist Rami Jaffee has said: "What I did notice is that kind of upbeat song with some pretty scary lyrics." Dylan painted the album's cover art himself.  On October 14, 2004, the Warren Zevon tribute album Enjoy Every Sandwich: The Songs of Warren Zevon was released, on which the Wallflowers covered Zevon's 1978 song "Lawyers, Guns and Money." In promotion of the album, the Wallflowers performed "Lawyers, Guns and Money" on the Late Show with David Letterman with Zevon's son, Jordan, on October 12, 2004.  On October 31, 2004, the Wallflowers were flown via military transport plane to the USS John C. Stennis aircraft carrier in the middle of the Pacific Ocean to perform for the returning troops.  Rebel, Sweetheart was released on May 24, 2005, and was met with positive reviews. Despite widespread critical acclaim, Rebel, Sweetheart performed relatively poorly commercially, peaking at No. 40 on the Billboard 200. However, the first single from the album, "The Beautiful Side of Somewhere", hit No. 5 on AAA radio. The second single was "God Says Nothing Back". This was the first Wallflowers album to be released on DualDisc. On one side was the album, and on the other was a DVD that included exclusive performances and arrangements of some of the band's songs, as well as an interview with comedian Jon Lovitz. In promotion of the album, the Wallflowers did concerts for the Oxygen Custom Concert Series and PBS Soundstage. Around the time of the album's release, the band set out on what would be their last tour for two years. They were joined by Stuart Mathis on lead guitar. After 2005, the Wallflowers ended their relationship with Interscope Records.
Question: Why did Stuart join?
Answer: 

Problem: Background: Martina Hingis (born 30 September 1980) is a Swiss former professional tennis player who spent a total of 209 weeks as the singles world No. 1 and 90 weeks as doubles world No. 1, holding both No. 1 rankings simultaneously for 29 weeks. She won five Grand Slam singles titles, thirteen Grand Slam women's doubles titles, winning a calendar-year doubles Grand Slam in 1998, and seven Grand Slam mixed doubles titles; for a combined total of twenty-five major titles. In addition, she won the season-ending WTA Finals two times in singles and three times in doubles, and an Olympic silver medal.
Context: In 2001, Switzerland, with Hingis and Roger Federer on its team, won the Hopman Cup. Hingis didn't drop a set in any of her singles matches during the event, defeating Tamarine Tanasugarn, Nicole Pratt, Amanda Coetzer, and Monica Seles. Federer was later quoted as saying: "I learned a lot from her, especially the two years I was here - once as a hitting partner and once as a partner with Martina. Definitely she helped me to become the player I am today."  Hingis reached her fifth consecutive Australian Open final in 2001, defeating both of the Williams sisters en route, before losing to Jennifer Capriati. She briefly ended her coaching relationship with her mother Melanie early in the year but had a change of heart two months later just before the French Open. 2001 was her least successful year in several seasons, with only three tournament victories in total. She lost her No. 1 ranking for the last time (to Jennifer Capriati) on 14 October 2001. In that same month, Hingis underwent surgery on her right ankle.  Coming back from injury, Hingis won the Australian Open doubles final at the start of 2002 (again teaming with Anna Kournikova) and reached a sixth straight Australian Open final in singles, again facing Capriati. Hingis led by a set and 4-0 and had four match points but lost in three sets. In May 2002, she needed another ankle ligament operation, this time on her left ankle. After that, she continued to struggle with injuries and was not able to recapture her best form.  In February 2003, at the age of 22, Hingis announced her retirement from tennis, due to her injuries and being in pain. "I want to play tennis only for fun and concentrate more on horse riding and finish my studies." In several interviews, she has indicated she wishes to return to her home country and coach full-time.  During this segment of her tennis career, Hingis won 40 singles titles and 36 doubles events. She held the World No. 1 singles ranking for a total of 209 weeks (fifth most following Steffi Graf, Martina Navratilova (after whom she was named), Chris Evert, and Serena Williams). In 2005, Tennis magazine put her in 22nd place in its list of 40 Greatest Players of the TENNIS era.
Question: When was her first retirement from tennis?
Answer:
February 2003,