INFORMATION RETRIEVAL A book by C. J. van RIJSBERGEN B.Sc., Dip. NAAC, Ph.D., M.B.C.S., F.I.E.E., C.Eng., F.R.S.E. Information Retrieval Group, University of Glasgow PREFACE TO THE SECOND EDITION (London: Butterworths, 1979) The major change in the second edition of this book is the addition of a new chapter on probabilistic retrieval. This chapter has been included because I think this is one of