Original sentence: In physics and mathematics, a pseudoscalar is a quantity that behaves like a scalar, except that it changes sign under a parity inversion such as improper rotations while a true scalar does not.ru:Псевдоскаляр
Edited sentence: (e1, e2) → (u1, u2).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 this setting, a pseudoscalar changes sign under a parity inversion, since if.It is these scalar-like properties which give rise to its name.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.e1e2 → u1u2 = ±e1e2,.is a change of basis representing an orthogonal transformation, then.ru:ПсевдоскалярIn physics, a pseudoscalar is a quantity that behaves like a scalar, except that it changes sign under a parity inversion such as improper rotations while a true scalar does not.where the sign depends on the determinant of the rotation