The assignment for our class is different from that for Whiteley's in
several respects. So go by this, not by his list of questions.
- 5.3.3 b.
(I did not say this in class on 29 January,
but a SYMLOG printout is preferable here.)
- 5.4.1 b.
Note that this true-false statement
has an understood "For ALL \alpha, ..."
at the beginning of it.
So, in line with my remarks in the posting to our discussion list a week
or two ago, you must give a general argument for the truth of this statement
if you say it is true, whereas if you say it is false, then a single
specific counterexample is enough to support your claim of falsehood.
- 5.4.4 f.
Give a SYMLOG printout of an SD-derivation that derives
both \alpha and \not \alpha, for some wff \alpha of your choice.
- 5.4.5 d.
Again, give a SYMLOG printout. And of course you
will have to understand precisely the definition (in class and in the
book) of "SD-inconsistent", and also the "Test for Derivability", before
you even know what your printout should contain.... :-)
- 5.4.7 h. (yes, SYMLOG printout again)
- For each of the arguments in (a) through (b) below,
(i) give an SD-derivation (SYMLOG printout) of the conclusion
from the premise(s), and
(ii) give an English argument that, as closely as possible,
paraphrases the SD-der. you gave in (i). (Examples of what I mean
here will be given in class.) It may be fair to say that what I do
when I have to construct a derivation is to map out an English version
of it first; I certainly think in English rather than in SD! :-)
(a) A -> B (b) \not A v B (c)
---------------- ---------- ----------
\not B -> \not A A -> B A v \not A