It’s a long flight, and not the most comfortable (thanks, BA). But lovely to be in the Bahamas again, on a family visit. Brexit news inescapable but all seeming particularly mad from this distance. Time for a lot of reading. I’ve particularly enjoyed Jonathan Raban’s Coasting (again!), Jill Paton Walsh’s A Desert in Bohemia and am devouring Sally Rooney’s rightly much praised Normal People. Time too for re-thinking the dratted intro logic book: another month, another conception emerges of how best to organize things — but I hope there is at last convergence on a satisfying solution rather than just a continuing random walk though the options!
Tsk, tsk, it’s because you’re not using ND Gentzen style. I’ve been teaching it this semester, and it has worked really well with the students. I’ve taught tableaux and Fitch style in the past. Tableaux are confusing: they are essentially semantic, and they are not so related to the way we reason. Gentzen style proofs are much more perspicuous than Fitch style proofs: one can ‘take in’ even complicated proofs at a glance.
The book will hunt you as long as you won’t settle for the right proof system!