We compare the delta lenses, also known as d-lenses, of Diskin et al. with the c-lenses, known to be equivalent to opfibrations, already studied by the authors. Contrary to expectation a c-lens is a d-lens but not conversely. This result is surprising because d-lenses appear to provide the same information as c-lenses, and some more besides, suggesting that the implication would be the reverse -- a d-lens would appear to be a special kind of c-lens. The source of the surprise can be traced to the way the two concepts deal differently with morphisms in a certain base comma category (G,1V). Both c-lenses and d-lenses are important because they extend the notion of lens to take account of the information available in known transitions between states and this has important implications in practice.
|Number of pages||18|
|Journal||Proceedings of the Second International Workshop on Bidirectional Transformations : BX 2013|
|Publication status||Published - 2013|
|Event||International Workshop on Bidirectional Transformations (2nd : 2013) - Rome, Italy|
Duration: 17 Mar 2013 → 17 Mar 2013
- Delta lens
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