MathDB

=A subset

S

\mathbb R^2

is called an algebraic set if and only if there is a polynomial

p(x,y)\in\mathbb R[x,y]

such that S \equal{} \{(x,y)\in\mathbb R^2|p(x,y) \equal{} 0\} Are the following subsets of plane an algebraic sets? 1. A square http://i36.tinypic.com/28uiaep.png 2. A closed half-circle http://i37.tinypic.com/155m155.png

Problem Statement