Notes on Galois Theory
... For simple extensions, the converse to Lemma 2 is true. In fact, we can say much more. Lemma 3: Let α be an element in an overfield L of a field K. Then: K(α)/K is algebraic ⇔ α is algebraic over K ⇔ K[α] = K(α) ⇔ [K(α) : K] < ∞. Moreover, if α is algebraic over K and f (X) =Irr(α, K), then there ex ...
... For simple extensions, the converse to Lemma 2 is true. In fact, we can say much more. Lemma 3: Let α be an element in an overfield L of a field K. Then: K(α)/K is algebraic ⇔ α is algebraic over K ⇔ K[α] = K(α) ⇔ [K(α) : K] < ∞. Moreover, if α is algebraic over K and f (X) =Irr(α, K), then there ex ...
Intersection Theory course notes
... To extend the Fundamental Theorem of Algebra to non-generic polynomials we need the notion of the multiplicity of a root. There are two equivalent definitions. Algebraic definition of multiplicity. A root a of f has multiplicity k iff f (a) = f 0 (a) = . . . = f (k−1) (a) = 0, andf (k) (a) 6= 0. Geo ...
... To extend the Fundamental Theorem of Algebra to non-generic polynomials we need the notion of the multiplicity of a root. There are two equivalent definitions. Algebraic definition of multiplicity. A root a of f has multiplicity k iff f (a) = f 0 (a) = . . . = f (k−1) (a) = 0, andf (k) (a) 6= 0. Geo ...
Polynomial
In mathematics, a polynomial is an expression consisting of variables (or indeterminates) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents. An example of a polynomial of a single indeterminate (or variable), x, is x2 − 4x + 7, which is a quadratic polynomial.Polynomials appear in a wide variety of areas of mathematics and science. For example, they are used to form polynomial equations, which encode a wide range of problems, from elementary word problems to complicated problems in the sciences; they are used to define polynomial functions, which appear in settings ranging from basic chemistry and physics to economics and social science; they are used in calculus and numerical analysis to approximate other functions. In advanced mathematics, polynomials are used to construct polynomial rings and algebraic varieties, central concepts in algebra and algebraic geometry.