The theory of integrative levels and its relevance to the design of information systems

The Classification Research Group was founded early in the 1950s and Leo Jolley joined a few years later. He was not able to attend every meeting, but when he did, he usually came armed with a very substantial contribution, and between meetings he regularly wrote in to comment on the minutes which he had received. He was a valued friend, and from conversations with him I know that he found the CRG meetings stimulating, and I believe that it was particularly in this area of the theory of integrative levels that he derived a good deal of value himself from our meetings.