The cross product does not readily generalise to other dimensions, though the closely related exterior product does, whose result is a bivector. In two dimensions this is simply a pseudoscalar ( a 1 e 1 + a 2 e 2 ) ∧ ∧ ( b 1 e 1 + b 2 e 2 ) = ( a 1 b 2 − − a 2 b 1 ) e 1 e 2 .