Original sentence: A pseudoscalar in a geometric algebra is a highest-grade element of the algebra.For example, in two dimensions there are two basis vectors, ,  and the associated highest-grade basis element is.In physics, a pseudoscalar is a quantity that behaves more or less like a scalar, except that it transforms oddly under the action of a discrete group.In this setting, a pseudoscalar changes sign under a parity inversion, since if (e1, e2) → (u1, u2) is a change of basis representing an orthogonal transformation, then e1e2 →  u1u2 = ±e1e2, where the sign depends on the determinant of the rotation.Mathematically, a pseudoscalar is an element of the top exterior power of a vector space.More generally, it is an element of the canonical bundle of a differentiable manifold.Pseudoscalars in geometric algebra thus correspond to the pseudoscalars in physics.So a pseudoscalar is a multiple of e12.The element e12 squares to −1 and commutes with all elements — behaving therefore like the imaginary scalar i in the complex numbers
Edited sentence: A pseudoscalar in a geometric algebra is the highest-grade basis element of the algebra.For example, in two dimensions there are two basis vectors, ,  and the highest-grade basis element is.In mathematics and physics, a pseudoscalar is a quantity that behaves more or less like a scalar, except that it transforms oddly under the action of a discrete group.Indeed, the language of the geometric algebra provides for a cleaner notation for the concept of the pseudoscalar than does the traditional physics notation; this is one of the claimed strengths of the geometric algebra notation.Pseudoscalars in geometric algebra correspond to the pseudoscalars in physics.The notation used in geometric algebra provides a mathematically cleaner, less ambiguous notation for the concept, as compared to the traditional physics notation.This element squares to −1 and commutes with all elements — behaving therefore like the imaginary scalar i in the complex numbers