| Article ID: | iaor1992349 |
| Country: | Netherlands |
| Volume: | 32 |
| Issue: | 2 |
| Start Page Number: | 183 |
| End Page Number: | 193 |
| Publication Date: | Jul 1991 |
| Journal: | Discrete Applied Mathematics |
| Authors: | Niemi Valtteri |
The class of all languages can be seen as a distributive lattice with respect to a preorder defined by letter-to-letter morphisms. Maximal dense intervals in the lattice are investigated. The results are based on a construction that builds a new language, so-called power language, from subsets of a given language. Applications to grammar form theory and graph theory are also presented.