Content deleted Content added
Adam Sampson (talk | contribs) Fix retrenchment link |
Adam Sampson (talk | contribs) m Fix botched edit |
||
Line 3:
For example, <i>x'</i> ∈ {1,2,3} (where <i>x'</i> is the value of the [[variable]] <i>x</i> after an operation) could be refined to <i>x'</i> ∈ {1,2}, then <i>x'</i> ∈ {1}, and implemented as <i>x</i> := 1. Implementations of <i>x</i> := 2 and <i>x</i> := 3 would be equally acceptable in this case, using a different route for the refinement. However, we must be careful not to refine to <i>x'</i> ∈ {} (equivalent to <i>false</i>) since this is unimplementable; it is impossible to select a [[member]] from the [[empty set]].
The term [[Reification (computer science)|reification]] is also sometimes used (coined by [[Cliff Jones]]). [[Retrenchment (computing)|Retrenchment]] is an alternative technique when formal refinement is not possible. The opposite of refinement is [[Abstraction (computer science)|abstraction]].
[[Category:Formal methods]]
| |||