Projects and Assignments in Pure Mathematics

The p-adic numbers

The real numbers are obtained from the rationa numbers by `completing', i.e. adding limits of Cauchy sequences, with respect to Cauchy sequences. For any prime p, there is another `metric' or distance on the rational numbers. By completing with respect to this, one obtains the field Q_p of p-adic numbers. This has strange properties: for example, all triangles are isosceles. The project could take various directions, for example the Hasse principle, that a quadratic form over Q has a rational solution if and only if it has a solution in the reals and in all fields Q. Another direction for the project would be to develop the general theory of valued fields.

Books

J.W.S. Cassels, Local fields, Cambridge Univ. Press, 1986.
P. Ribenboim, The theory of classical valuations, Springer, 1998.

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