| What follows is not a strict fugue, but a fugato in five-part invertible counterpoint. |
| The idea haunted him like the invertible companions of Orestes. |
| In 1911 he established his theorems on the invariance of the dimension of a manifold under continuous invertible transformations. |
| He spent about a year of rigorous self-study fooling around with canons, fugues, invertible counterpoint, and so on. |
| But because cryptographic functions must be invertible, must be fast to compute, and should have small key size and memory requirements, linear functions are irresistible. |
| Projective transformations, which are invertible linear changes of homogeneous coordinates, are given by matrix multiplication. |
