Sentence examples for nabla from inspiring English sources

There were few mistakes, mostly NALLA for NABLA, and your favourite clue, of 18 nominated at least once, was 'He likes to think he's a good saxophonist but he isn't' for OBECHE, three votes ahead of 'After a rough voyage there's many a bonking in the quayside inn!' (SUNDRI).

More intriguingly, Łukasiewicz notes that there is another possibility operator $\nabla$ with the truth-table also given below: Taken in isolation, this is indistinguishable from $\Delta$, but the two operators together interact differently, for while $\dashv \Delta\Delta p$ and $\dashv \nabla\nabla p$, both $\vdash \Delta\nabla p$ and $\vdash \nabla\Delta p$.