http://query.nytimes.com/gst/fullpage.html?res=9F02E1DE1438F932A2575AC0A9679C8B63&sec=&spon=&pagewanted=print Now he has written a book, ''Fugitive Days'' (Beacon Press, September). Mr. Ayers, who is 56, calls it a memoir, somewhat coyly perhaps, since he also says some of it is fiction. He writes that he participated in the bombings of New York City Police Headquarters in 1970, of the Capitol building in 1971, the Pentagon in 1972. But Mr. Ayers also seems to want to have it both ways, taking responsibility for daring acts in his youth, then deflecting it. ''Is this, then, the truth?,'' he writes. ''Not exactly. Although it feels entirely honest to me.'' But why would someone want to read a memoir parts of which are admittedly not true? Mr. Ayers was asked. ''Obviously, the point is it's a reflection on memory,'' he answered. ''It's true as I remember it.''