NEW YORK SO MANY MAJOR DEALS for paperback rights are being made in advance of hardcover publication that few important books (important in a money sense) are coming to auction these days. But, surprisingly, one of them is -- Erich Segal's third novel, Man, Woman and Child. To be published this spring by Harper & Row, the novel is an option book of Avon's, which bought Segal's last novel, Oliver's Story for something like a million and a half. The new book was offered to Avon Books first, but the price was, in the words of Avon's publisher Walter Meade, "an arm and a leg," and he let the book go to auction. He still retains a topping privilege -- that is, he may top the highest bid by 10 percent, but only (only!) up to $1 million; after that, no topping. Should be an interesting auction.

Meanwhile, Avon has hardly been idle. They've acquired J. Patrick Wright's On a Clear Day You Can See General Motors at auction for $274,500; and it is said they hold the floor bid for the auction of Larry Collin's and Dominique LaPierre's new book, The Fifth Horseman, at around $750,000. And, sometime this fall, Avon will launch the paper edition of Oxford American Dictionary simultaneously with Oxford University Press' hardcover edition. Avon hopes to have it ready by the American Booksellers convention in June, but they're going to hold their big sales pitch off until Spring 1981, to establish the dictionary's credentials and allow word-of-mouth interest to build. Meade predicts it will be "the dominant qualtiy dictionary in the United States in two years. It has the feel, it has the authority of Oxford University Press and it's extraordinarily useful."

They were popping champagne corks recently at Bantam Books when they read the latest best-seller list and found that they own reprint rights to the top five (at this writing) novels: Princess Daisy, Smiley's People, The Devil's Alternative, The Bourne Identity and Portraits. They also own a former No. 1 best seller, Sophie's Choice. On the nonfiction sale, they have acquired The Pritikin Program for Diet and Exercise and The Right Stuff, both of which have been on the lists a long time. (The above totals alone must add up to at least $8 million.) Success of this magnitude may never have happened in the book reprint business before. It certainly hasn't happened at Bantam.

Charles Scribner's Sons hopes that P. D. James' Innocent Blood will be one of the biggest sellers of the year, and so far circumstances are supporting these hopes. Despite its title, this is James' first non-detective novel; Book-of-the-Month has picked it up for a Main Selection; movie rights have been optioned, and Fawcett has purchased reprint rights. Scribner's says that paperback rights went for "very high six figures," and Arlene Friedmen, editor-in-chief of Fawcett Books, agrees. "High," she says, underlining it twice with her voice. (The word around town is that it went for more than $300,000. High indeed.)

Also at Fawcett, Friedman is particularly enthusiastic about Susan Howatch's latest, Sins of the Fathers. As the paperback publishers of Howatch's Cashelmara and The Rich Are Different, Fawcett has some idea of what to expect in terms of the best-seller list. Did they pay more for Sins of the Fathers than they did for The Rich Are Different? "You never pay less," says Friedman solemnly. "They never, never let you pay less."

Now that New American Library has acquired Irving Wallace under a prime contract giving NAL all rights, hardcover and paperback, they have four top-selling novelists under such contracts: Wallace, Stephen King, Erica Jong and Ken Follett. There was a tiny scuffle recently that underlined the significance of this. Viking Press sent out a press release announcing that Stephen King had signed with Viking Press for three books, the first of which, Firestarter, will be published in September. This announcement sat very poorly with NAL; in fact, it made them quite angry. A flustered Viking sent out a new release admitting its error -- Viking had, in fact, signed the contract with NAL, not King, and King's contract was with NAL, not Viking. And, since NAL is venturing once more into the hardcover business, it is possible that errors like these may not occur again, and that NAL will keep its best authors for its own line.

Whenever I think of paperbacks, I think of Dover Publications, because I have more Dover books on my permanent shelves than those of any other publisher. They have a great new list of titles shaping up, among them: Fifty Great American Silent Films 1912-1912, A Pictorial Survey, edited by Anthony Slide and Edward Wagenknecht; and Old Washington in Early Photographs, edited by Robert Reed. The two I can't wait to get my hands on are The Chicago Worlds's Fair A Photographic Record of the 1893 Fair edited by Stanley Appelbaum and The Golden Age of the Luxury Car; An Anthology of Articles and Photographs from "Autobody" edited by George Hilderbrand. I find it very hard to give a Dover book away, and I almost never lend them, because they don't come back.

Holt, Rinehart & Winston are going into the trade paperback business, with a new imprint, Owl Books. They will be acquiring titles not only from their blacklist, but from other publishers' lists and from new Holt books, which they intend to bid for at auction, just like anybody else. They are also putting their two top cartoonists, Garry "Doonesbury" Trudeau and Charles M. "Peanuts" Schulz into Owl covers, which is a bit puzzling, since both of those authors are already in Holt paper covers. Warner Books will be involved in a co-publishing venture with Prentice-Hall, to bring out Dr. London Smith's new book, Encyclopedia of Baby and Child Care. Dr. Smith, known as "The Children's Doctor," is the author of the phenomenally successful Feed Your Kids Right, which Dell Delta is publishing as a trade paperback in April. Prentice-Hall will edit the new book; Warner will produce it; both houses will share costs, and their editions -- Prentice-Hall's hardcover and Warner's trade paper -- will come out simultaneously sometime this fall.

In October, Warner will publish Norman Mailer's The Executioner's Song, on which the house holds the prime contract, having leased it to Little, Brown. No price as yet has been set for the 992-page paperback (1,056 pages and $16.95 in cloth) but it might break new barriers for mass-market cover pricing. Since nothing succeeds like success, Warner is giving a new look to its long-time No. 1 trade paperback best seller, Mary Ellen's Best of Helpful Hints. Not satisfied with a mere 1,405,000 in print at $3.95, they will produce a paper-over-boards gift edition, with interior spiral binding, at $7.95 in the fall of this year.

I could go on and on and on, but I've been busy giving my cat The Cat I.Q. Test, by Elizabeth Bard (Doubleday Dolphin paperback, to be published in May). I'm sure you'll be happy to know that, by elimination of a handful of questions that have nothing to do with her, I made Mitzi come out a genius.