Sensors, or tests, are central in our analysis of the state of our surroundings. We examine the possible relations among two sensors which are both (imperfectly) able to discriminate between the same pair of states of the object of interest. We show that, in principle, (1) each such pair has a range of possible performance when used optimally (2) in general, two sensors, even 'good ones' cannot be combined to be perfect and (3) every sensor has, in principle, a magic partner sensor such that the two of them together can, if the relation between them is at its limit, be perfect. We speculate briefly on the role of this result in technological and natural systems, and its implications for the discovery of mechanisms in the natural sciences. Research supported in part by the NSF and by the AFOSR.

Paul B. Kantor Biography:

Paul Kantor's research centers on the role of information systems for storage and retrieval in a wide range of applications, with particular emphasis on rigorous evaluation of the effectiveness of such systems. At Rutgers he is a member of the Department of Library and Information Science, and Research Director of the CCICADA Center. He is also a member of the graduate faculty of the Center for Operations Research (RUTCOR),and of the Department of Computer Science, and is a member of the Center for Discrete Mathematics and Computer Sciences (DIMACS)

He is a member of the American Society for Information Science and Technology (ASIST), the American Association for the Advancement of Science (AAAS), the IEEE, the American Physical Society, and the American Statistical Association. His research has been supported by such agencies as the NSF, DARPA, ARDA and the US Department of Education. He was educated in Physics and Mathematics at Columbia and Princeton, has received the ASIST Research award, and is a Fellow of the AAAS.