Question: Robert Chapin has trained with which late stand-up comedian and actor from San Francisco?

Context paragraphs:
Ronnie Schell: Ronald Ralph "Ronnie" Schell (born December 23, 1931) is an American actor, stand-up comedian, and voice actor.  He appeared on May 28, 1959, episode of the TV quiz program "You Bet Your Life", hosted by Groucho Marx.  Schell demonstrated a comic barrage of beatnik jive talk.  As a stand-up comedian, he first developed his act at the world-famous hungry-i nightclub in San Francisco, California.  Schell is probably best known in his 1960s television role as Duke Slater in "Gomer Pyle, U.S.M.C."

The Hunted (2015 film): The Hunted is a 2015 American feature film based on the action comedy web series The Hunted (2001) created by Robert Chapin.  It tells the story of a struggling actor who leads a group of misfit slayers against an army of vampires.  The film is one of the first features produced under SAG’s New Media contract and takes advantage of the latest in online distribution through Vimeo VOD (which includes Apple TV, Roku, Xbox, and smart TVs).

Robert Chapin: Robert Chapin (born April 3, 1964 in Miami, Florida), is a stunt, fight and swordplay choreographer, visual effects artist and supervisor, actor, writer, director, and producer.  He is popularly known for acting in and creating the longest running action horror web series called The Hunted.  He is also known for creating visual effects for American Beauty, Crouching Tiger, Big Lebowski and X-Men.  Chapin first starred in a film called "Ring of Steel", of which he also wrote.  As a fight choreographer and instructor, he is certified with the Societies of American, British, and Canadian Fight Directors.  He has trained with stars such as Plácido Domingo, Robin Williams, David Hasselhoff, John Saxon, Marc Singer, Richard Grieco, Richard Lynch, Mike Norris, James Lew, Olivier Gruner, Jeff Conaway, Raye Hollitt, Tessie Santiago, and Angelica Bridges.

Bill Cosby: William Henry Cosby Jr. ( ; born July 12, 1937) is an American stand-up comedian, actor, musician, and author.  His start in stand-up comedy began at the hungry i in San Francisco; he then landed a starring role in the 1960s television show "I Spy".  He was also a regular on the children's television series "The Electric Company" during the show's first two seasons.

Michael Yo: Michael Yo Simmons (born November 20, 1974) is an American actor, TV Host, Hollywood expert and stand-up comedian.  He currently co-hosts The Insider on CBS, as well as Yo Show on Yahoo! TV, which garners an average of 1.5 million views per episode.  Yo also appears regularly on the comedy panel of E!'s Chelsea Lately and as a guest host for The Talk on CBS.  Yo continues to appear as a Pop Culture expert on HLN's Showbiz Tonight hosted by A.J. Hammer.  Michael tours the country as a professional stand-up comedian, appearing at the Improv’s, Stand-Up Live, Palms Hotel, Laugh Factory, Comedy Store, and Comedy Juice among others.  His Hot Mess Tour also performs at colleges throughout the country.

San Francisco City Guides: San Francisco City Guides (SFCG) is a non-profit organization that offers over 90 different walking tours of San Francisco presented by trained, volunteer guides.  San Francisco City Guides was founded in 1978 as a program of the San Francisco Public Library (SFPL) and the San Francisco Parks Alliance.  Tours are offered daily, regardless of weather.  Reservations are accepted for groups of eight or more, as well as for special date or time requests.

Marina Green: The Marina Green in San Francisco, California, is a 74 acre expanse of grass between Fort Mason and the Presidio.  It is adjacent to San Francisco Bay, and this location provides good views of the Golden Gate Bridge, Angel Island, Alcatraz Island, and parts of Marin County.  Houses built mostly in the 1920s and 1930s line Marina Boulevard, the southern boundary of the Marina Green.  Many of these houses have large bay windows, and Herb Caen, the late San Francisco newspaper columnist, often made references to the immaculate furnishings behind these windows.  In the past, a railroad track along the southern edge of the Marina Green allowed the San Francisco Belt Railroad to serve the Presidio.  Adjacent to the Marina Green is a marina, home to the St. Francis Yacht Club and the Golden Gate Yacht Club.  The San Francisco Bay Trail runs through the green.

San Francisco Comedy Competition: The San Francisco Comedy Competition (sometimes referred to as the San Francisco International Comedy Competition or The San Francisco International Stand-Up Comedy Competition) is a stand-up comedy contest held each September in San Francisco, California, and neighboring areas of Northern California.

UCSF School of Medicine: The UCSF School of Medicine, is the medical school of the University of California, San Francisco, United States, and is located in San Francisco.  Founded in 1864 by Hugh Toland, it is the oldest medical school in California and the western United States.  The school is affiliated with the UCSF Medical Center, which was ranked in 2017 as the #1 hospital in California and the #5 in the United States.  UCSF faculty have treated patients and trained residents since 1873 at the San Francisco General Hospital and for over 50 years at the San Francisco VA Medical Center.

Robin Williams: Robin McLaurin Williams (July 21, 1951 – August 11, 2014) was an American stand-up comedian and actor.  Starting as a stand-up comedian in San Francisco and Los Angeles in the mid-1970s, he is credited with leading San Francisco's comedy renaissance.  After rising to fame as Mork in "Mork & Mindy" (1978–82), Williams established a career in both stand-up comedy and feature film acting.  He was known for his improvisational skills.

Supporting paragraphs: Robert Chapin Robin Williams
Answer: Robin McLaurin Williams