user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: greg beatty contributed to a book edition from what publisher? 
Knowledge Triplets: Robert Weinberg, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Robert Silverberg
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Catherine Asaro
Nebula Awards Showcase 2010, book.publishing_company.books_published, Roc
Harry Harrison, book.author.contributing_author_to, Nebula Awards Showcase 2010
Jody Lynn Nye, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Ursula K. Le Guin
John Kessel, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Ysabeau S. Wilce
F. J. Bergmann, book.author.contributing_author_to, Nebula Awards Showcase 2010
Ysabeau S. Wilce, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Tom Doherty
Nina Kiriki Hoffman, book.author.contributing_author_to, Nebula Awards Showcase 2010
9780451463166, book.isbn.book_editions, Nebula Awards Showcase 2010
Elizabeth Anne Hull, book.author.contributing_author_to, Nebula Awards Showcase 2010
Robert Silverberg, book.author.contributing_author_to, Nebula Awards Showcase 2010
Lynn Abbey, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Greg Beatty
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Frederik Pohl
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Kate Wilhelm
Nebula Awards Showcase 2010, book.book_edition.publisher, Roc
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, John Kessel
Kate Wilhelm, book.author.contributing_author_to, Nebula Awards Showcase 2010
Greg Beatty, people.person.education, m.02wp31m
Nebula Awards Showcase 2010, book.book_edition.publication_date, 2010-04
Greg Beatty, people.person.education, m.0n1mftk
Martin H. Greenberg, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Algis Budrys
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Robert Weinberg
Greg Beatty, people.person.gender, Male
Frederik Pohl, book.author.contributing_author_to, Nebula Awards Showcase 2010
Greg Beatty, people.person.nationality, United States of America
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Kevin J. Anderson
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Elizabeth Anne Hull
Tom Doherty, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.isbn, 9780451463166
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Jody Lynn Nye
Nebula Awards Showcase 2010, book.book.editions, Nebula Awards Showcase 2010
David Drake, book.author.contributing_author_to, Nebula Awards Showcase 2010
Mike Resnick, book.author.contributing_author_to, Nebula Awards Showcase 2010
m.02wp31m, education.education.student, Greg Beatty
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Harry Harrison
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, M. J. Engh
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Nina Kiriki Hoffman
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Martin H. Greenberg
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Catherynne M. Valente
Bill Fawcett, book.author.contributing_author_to, Nebula Awards Showcase 2010
Catherine Asaro, book.author.contributing_author_to, Nebula Awards Showcase 2010
Ursula K. Le Guin, book.author.contributing_author_to, Nebula Awards Showcase 2010
m.0n1mftk, education.education.student, Greg Beatty
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Bill Fawcett
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Mike Resnick
Kevin J. Anderson, book.author.contributing_author_to, Nebula Awards Showcase 2010
Greg Beatty, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, David Drake
Algis Budrys, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, Lynn Abbey
Catherynne M. Valente, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.contributing_authors, F. J. Bergmann
Greg Beatty, book.book_edition.contributing_authors, Nebula Awards Showcase 2010
M. J. Engh, book.author.contributing_author_to, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book.first_edition, Nebula Awards Showcase 2010
Roc, book.publishing_company.books_published, Nebula Awards Showcase 2010
Nebula Awards Showcase 2010, book.book_edition.book, Nebula Awards Showcase 2010

Answer: Roc