With IFL2 (the book itself) temporarily put aside, I’m turning to the task of putting together its associated webpages.
The initial effort will go into supplying answers to the end-of-chapter exercises. This might take a little while! (Even when there is a significant overlap with the exercises for IFL1, I’ll have to LaTeX all the solutions for the first time.)
One task, though, is already done. Regular readers here will know — heavens, I’ve bored on about it often enough! — that while IFL1 did logic by truth trees, IFL2 instead uses a Fitch-style natural deduction system. However, if you are fan of trees, all is not lost. I’m making material on trees available as online supplements. These are now available.
So you will find linked here two PDFs. The first, already pre-circulated here, is heavily rewritten from the propositional truth-tree material in IFL1. The second contains three chapters on quantification trees, a pre-revision version soon to be replaced with an improved one! Both PDFs should be of some use to students who want to know about trees (or would like supplementary reading for a tree-based course) even if they aren’t using IFL2. So long as you know something of the basics of propositional logic and truth-tables, and then know the language of quantificational logic, both documents should be quite accessible.
6 thoughts on “Truth trees for propositional and predicate logic”
why the switch from truth trees to natural deduction?
I’m not going to repeat all the pros and cons of ND vs trees in a first logic course, which I’ve touched on in earlier blog posts! And the arguments are finely balanced, in my view. Let’s just say that natural deduction is more — how shall we put it? — natural (closer to regimenting ordinary multi-step arguments).
I don’t know about others, but my personal experience when preparing sample answers for class exercises, exams and books is that the job inevitably leads me to seeing better ways in which the exercises could have been formulated or chosen, and sometimes better ways of articulating bits of text. So I wonder whether your work on solutions to exercises for IFL2 is having the same repercussions…
Yes, at least in mercifully small ways (so far!) …
Yes, it will remain freely available (though if I have time and energy, I’d hope to update, improve, the QL part rather than simply reproduce the old chapters).
I would like to recommend the on-line truth-tree material to students. Can I assume that it will remain freely available — or will CUP be putting a price on it?