*In which we encounter some methods for factorising a large number.*

- Description of
*Fermat factorisation*. - Definition of
*least absolute residue*. (See also Gauss’s lemma, in lecture 7.) - Definition of a
*factor base*and of a*-number*. - Description of the
*factor-base method*.

#### Further reading

Koblitz (*A Course in Number Theory and Cryptography*) and recent editions of Davenport (*The Higher Arithmetic*) both cover this material nicely.

#### Preparation for Lecture 24

As we saw, the factor-base method relies on coming up with a suitable factor base and suitable -numbers. How could continued fractions help us with this?

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November 30, 2011 at 12:11 pm

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