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Counting p-groups

Here we provide access to functions which count the number of d-generator p-class 2 groups. For details of the algorithm used see [EO99].

SetVerbose ("ClassTwo", 1) will provide information on the progress of the algorithm.

ClassTwo(p, d : parameters) : RngIntElt, RngIntElt -> SeqEnum
ClassTwo(p, d, Step : parameters) : RngIntElt, RngIntElt, SeqEnum -> SeqEnum
ClassTwo(p, d, s : parameters) : RngIntElt, RngIntElt, RngIntElt -> RngIntElt
Count the d-generator p-groups of p-class 2. If s or Step is supplied, then count only those of order p^((d + s)) or p^((d + m)) for m in Step. In the first two invocations, the sequence returns a sequence of length d choose 2, whose m-th entry is the number of groups of p^((d + m)). (Some additional entries may be deduced on the basis of duality.) The last invocation returns the number of groups of p^((d + s)).

     Exponent: RngIntElt                 Default: 0

If Exponent is true, count those groups which have exponent p.


Example GrpPGp_ClassTwo (H20E6)

Count the number of 3-generator p-class 2 5-groups.

> ClassTwo(5, 3);
[ 4, 19, 42, 19, 4, 1 ]
For example, the number of 3-generator 5-groups of order 5^6 and p-class 2 is precisely 42.

Count the number of 4-generator p-class 2 5-groups of order 5^7.

> ClassTwo(5, 4, 3);
6598


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