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{\bf Doron Zeilberger }
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{\bf How Berger, Felzenbaum and Fraenkel Revolutionized \hfil\break
COVERING SYSTEMS The Same Way that George\hfil\break
Boole Revolutionized LOGIC}
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The Berger-Felzenbaum-Fraenkel approach to
Covering Systems is exposited. In particular their
gorgeous proof of the famous $a_n=a_{n-1}$ theorem for exact covering
systems (found independently by Jamie Simpson),
is reviewed, and the analogy of their approach to
Boolean tautologies in Disjunctive Normal Form is pointed out.
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