Problem: Quotient groups and subgroups together form a way of describing every group by its presentation: any group is the quotient of the free group over the generators of the group, quotiented by the subgroup of relations. The dihedral group D4, for example, can be generated by two elements r and f (for example, r = r1, the right rotation and f = fv the vertical (or any other) reflection), which means that every symmetry of the square is a finite composition of these two symmetries or their inverses. Together with the relations
What groups can be combined to describe every group?
The answer is the following: is the quotient of the free group over the generators of the group

Problem: The situation became so tense that war with the United States seemed imminent. On April 22, 1914, on the initiative of Felix A. Sommerfeld and Sherburne Hopkins, Pancho Villa traveled to Juárez to calm fears along the border and asked President Wilson's emissary George Carothers to tell "Señor Wilson" that he had no problems with the American occupation of Veracruz. Carothers wrote to Secretary William Jennings Bryan: "As far as he was concerned we could keep Vera Cruz [sic] and hold it so tight that not even water could get in to Huerta and . . . he could not feel any resentment". Whether trying to please the U.S. government or through the diplomatic efforts of Sommerfeld and Carothers, or maybe as a result of both, Villa stepped out from under Carranza’s stated foreign policy.
Pancho Villa seeked a conversation with which American President?
The answer is the following: President Wilson

Problem: The design and function of department stores in Germany followed the lead of London, Paris and New York. Germany used to have a number of department stores; nowadays only a few of them remain. Next to some smaller, independent department stores these are Karstadt (in 2010 taken over by Nicolas Berggruen, also operating the KaDeWe in Berlin, the Alsterhaus in Hamburg and the Oberpollinger in Munich), GALERIA Kaufhof (part of the Metro AG). Others like Hertie, Wertheim and Horten AG were taken over by others and either fully integrated or later closed.
What cities influenced how department stores in Germany operated? 
The answer is the following: London, Paris and New York.

Problem: On April 4, 2008, Beyoncé married Jay Z. She publicly revealed their marriage in a video montage at the listening party for her third studio album, I Am... Sasha Fierce, in Manhattan's Sony Club on October 22, 2008. I Am... Sasha Fierce was released on November 18, 2008 in the United States. The album formally introduces Beyoncé's alter ego Sasha Fierce, conceived during the making of her 2003 single "Crazy in Love", selling 482,000 copies in its first week, debuting atop the Billboard 200, and giving Beyoncé her third consecutive number-one album in the US. The album featured the number-one song "Single Ladies (Put a Ring on It)" and the top-five songs "If I Were a Boy" and "Halo". Achieving the accomplishment of becoming her longest-running Hot 100 single in her career, "Halo"'s success in the US helped Beyoncé attain more top-ten singles on the list than any other woman during the 2000s. It also included the successful "Sweet Dreams", and singles "Diva", "Ego", "Broken-Hearted Girl" and "Video Phone". The music video for "Single Ladies" has been parodied and imitated around the world, spawning the "first major dance craze" of the Internet age according to the Toronto Star. The video has won several awards, including Best Video at the 2009 MTV Europe Music Awards, the 2009 Scottish MOBO Awards, and the 2009 BET Awards. At the 2009 MTV Video Music Awards, the video was nominated for nine awards, ultimately winning three including Video of the Year. Its failure to win the Best Female Video category, which went to American country pop singer Taylor Swift's "You Belong with Me", led to Kanye West interrupting the ceremony and Beyoncé improvising a re-presentation of Swift's award during her own acceptance speech. In March 2009, Beyoncé embarked on the I Am... World Tour, her second headlining worldwide concert tour, consisting of 108 shows, grossing $119.5 million.
When did Beyoncé get married?
The answer is the following:
April 4, 2008