Counting primes, groups and manifolds
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     Alex Lubotzky  (Jerusalem) 
   
    Let D be a finitely generated group. Let G be a semisimple Lie group,
    K a maximal compact subgroup and Y=G/K the associated symmetric
    space.   Let x be a positive real number (going to infinity).
    We will discuss questions of the following type:
    How many primes are there which are small than x ?
    How many subgroups D has, of index at most x?
    How many quotient manifolds Y has, of volume at most x?
    We will show that these seemingly unrelated questions are actually 
    connected in several different ways.