Answer the following question: Information: - The Nebula Awards annually recognize the best works of science fiction or fantasy published in the United States during the previous year. The awards are organized and awarded by the Science Fiction and Fantasy Writers of America (SFWA), a nonprofit association of professional science fiction and fantasy writers. They were first given in 1966 at a ceremony created for the awards, and are given in four categories for different lengths of literary works. A fifth category for film and television episode scripts was given 197478 and 200009. The rules governing the Nebula Awards have changed several times during the awards' history, most recently in 2010. - The Forever War series is a series of science fiction novels by Joe Haldeman. Not all of them take place in the same future universe. - Military science fiction is a subgenre of science fiction that features the use of science fiction technology, mainly weapons, for military purposes and usually principal characters that are members of a military organization involved in military activity; occurring sometimes in outer space or on a different planet or planets. It exists in literature, comics, film and video games. - Forever Peace is a 1997 science fiction novel by Joe Haldeman. It won the Nebula Award, Hugo Award and John W. Campbell Memorial Award in 1998. - Science fiction (often shortened to SF, sci-fi or scifi) is a genre of speculative fiction, typically dealing with imaginative concepts such as futuristic science and technology, space travel, time travel, faster than light travel, parallel universes, and extraterrestrial life. Science fiction often explores the potential consequences of scientific and other innovations, and has been called a "literature of ideas." It usually avoids the supernatural, and unlike the related genre of fantasy, historically science fiction stories were intended to have a grounding in science-based fact or theory at the time the story was created, but this connection is now limited to hard science fiction. - The Forever War (1974) is a military science fiction novel by American author Joe Haldeman, telling the contemplative story of soldiers fighting an interstellar war between Man and the Taurans. It won the Nebula Award in 1975, and the Hugo and the Locus awards in 1976. "Forever Free" (1999) and "Forever Peace" (1997) are, respectively, direct and thematic sequel novels. The novella "A Separate War" (1999) is another sequel of sorts, occurring simultaneously to the final portion of "The Forever War". Informally, the novels compose The Forever War series; the novel also inspired a comic book and a board game. - An interstellar war involves a warfare between combatants from different planetary systems. The concept provides a common plot device in science fiction, especially in the space opera subgenre. In contrast, the term "intergalactic war" refers to war between combatants from different galaxies; "interplanetary war" refers to war between combatants from different planets of the same solar system. - Forever Free is a science fiction novel by American author Joe Haldeman , the sequel to The Forever War . It was published in 1999 . - Joe William Haldeman (born June 9, 1943) is an American science fiction author. He is best known for his 1974 novel "The Forever War". That novel, and other of his works including "The Hemingway Hoax" (1991) and "Forever Peace" (1997), have won major science fiction awards including the Hugo Award and Nebula Award. For his career writing science fiction and/or fantasy he is a SFWA Grand Master and since 2012 a member of the Science Fiction Hall of Fame. - The Hemingway Hoax is a short novel by science fiction writer Joe Haldeman. It weaves together a story of an attempt to produce a fake Ernest Hemingway manuscript with themes concerning time travel and parallel worlds. A shorter version of the book won both a Hugo award and a Nebula award for best novella in 1991 (for stories in 1990). What is the relationship between 'forever free ' and 'the forever war series'?
Answer:
series