5.2. Non-Archimedian amoebas [04T3]
Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.
Complete original source context · Original author HTML
5.2. Non-Archimedian amoebas
If be an algebraic variety. The image is called the amoeba of , see [4]. Note that amoebas make sense also for varieties over other fields as long as we have a norm . The map is defined by and the amoeba of is defined to be .
A particularly useful case is when is an algebraically closed field with a non-Archimedian valuation. Recall that a non-Archimedian valuation is a function 22 2 Sometimes a valuation is defined as minus such a function. such that and . Note that gives a norm on and is nothing but taking the coordinatewise valuation.
Non-Archimedian amoebas of hypersurfaces were completely described in [7]. An example of such field is the field of the Puiseux series with complex coefficients in . Namely an element of is a formal series , where is any bounded from below set contained in a finite union of arithmetic progressions. The valuation is defined by . Note that we used irrational as well as rational powers in the Puiseux series to make the valuation surjective.