You are here

Algebraic number theory, a computational approach by Stein W.A.

By Stein W.A.

Show description

Read Online or Download Algebraic number theory, a computational approach PDF

Similar algebraic geometry books

Fukaya Categories and Picard-Lefschetz Theory

The critical items within the booklet are Lagrangian submanifolds and their invariants, reminiscent of Floer homology and its multiplicative constructions, which jointly represent the Fukaya classification. The proper facets of pseudo-holomorphic curve thought are lined in a few element, and there's additionally a self-contained account of the required homological algebra.

Additional info for Algebraic number theory, a computational approach

Sample text

The other inclusion is obvious by definition of ideal. 2. 3. Suppose I1 , . . , Is are pairwise coprime ideals. Then I1 is coprime to the product I2 · · · Is . Proof. 11); instead, we give a direct general argument. It suffices to prove the lemma in the case s = 3, since the general case then follows from induction. By assumption, there are x1 ∈ I1 , y2 ∈ I2 and a1 ∈ I1 , b3 ∈ I3 such x1 + y2 = 1 and a1 + b3 = 1. Multiplying these two relations yields x1 a1 + x1 b3 + y2 a1 + y2 b3 = 1 · 1 = 1.

Since p is prime, OK /p is an integral domain. Every finite integral domain is a field (see Exercise 10), so p is maximal, which completes the proof. If I and J are ideals in a ring R, the product IJ is the ideal generated by all products of elements in I with elements in J: IJ = (ab : a ∈ I, b ∈ J) ⊂ R. Note that the set of all products ab, with a ∈ I and b ∈ J, need not be an ideal, so it is important to take the ideal generated by that set (see Exercise 11). 6 (Fractional Ideal). A fractional ideal is a nonzero OK -submodule I of K that is finitely generated as an OK -module.

2 (LLL-reduced basis). The basis b1 , . . , bn for a lattice L ⊂ Rn is LLL reduced if for all i, j, 1 |µi,j | ≤ 2 and for each i ≥ 2, |b∗i |2 ≥ 3 − µ2i,i−1 |b∗i−1 |2 4 For example, the basis b1 = (1, 2), b2 = (3, 4) for a lattice L is not LLL reduced because b∗1 = b1 and b2 · b∗ 11 1 µ2,1 = ∗ 1∗ = > . b1 · b1 5 2 However, the basis b1 = (1, 0), b2 = (0, 2) for L is LLL reduced, since µ2,1 = b2 · b∗1 = 0, b∗1 · b∗1 and 22 ≥ (3/4) · 12 . LLL() [1 0] [0 2] 38 CHAPTER 2. 2 What LLL really means The following theorem is not too difficult to prove.

Download PDF sample

Rated 4.10 of 5 – based on 48 votes
Top