Mark, > On 11 Mar 2016, at 14:06, m...@proof-technologies.com wrote: > > Hi Dave, > > > With this rule, the theorems need to precisely match up with how they are > described in the manual, so you need to have the conclusion of the 2nd > theorem as the logical negation of the LHS of the "or" in the 1st thm (not > vice versa). So just use the double logical negation introduction rule on > the 2nd theorem, and then it works. Quite so. > > Perhaps using good old ASCII versions of the logical symbols a good idea. > This is what the HOL4 and HOL Light use. So there's: > disjunction: \/ > conjuntion: /\ > ...

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[Aside: actually HOL4 supports UTF-8-encoded Unicode maths symbols if you throw the right switches.] ProofPower now has support for UTF-8-encoded Unicode, but there isn’t any support for it in xpp yet. There is a program pputf8 that will translate ProofPower source into UTF-8. You can get pputf8 by taking a clone of the git repository g...@github.com:RobArthan/pp-contrib, navigating to pp-contrib/src/pputf8 and running: make -f pputf8.mkf bad Then copy the programs pputf8 (and utf8pp if you like) to somewhere convenient (e.g., $HOME/bin or the bin directory in your ProofPower installation). pputf8 is a filter, i.e., it reads standard input and writes standard output. Here is the result of running pputf8 on my recreation of David’s problem and Mark’s solution: val L1 = asm_rule ⌜p:BOOL⌝; val L2 = asm_rule ⌜p ⇒ q⌝; val L3 = undisch_rule L2; val L4 = asm_rule ⌜¬ q ∨ r ⌝; val L5 = ∨_cancel_rule L4 L3; (* Above fails with: Exception Fail * ¬ q ∨ r ⊢ ¬ q ∨ r and p ⇒ q, p ⊢ q are not of the form: `𝛤1 ⊢ t1 ∨ t2' and `𝛤2 ⊢ ¬t3' where ⌜t3⌝ is 𝛼-convertible to ⌜t1⌝ or ⌜t2⌝ [∨_cancel_rule.7050] * raised *) val L3' = ¬_¬_intro L3; val L5 = ∨_cancel_rule L4 L3'; (* Above works giving: val L5 = ¬ q ∨ r, p ⇒ q, p ⊢ r: THM *) If you run pp -d hol in a terminal window and then do: set_flag("input_in_utf8", true); set_flag("output_in_utf8", true); you should be able to execute the above commands by copying and pasting them into the terminal window. Alternatively, you can paste them into utf8pp >XYZ.ML and then work with XYZ.ML using xpp. I hope to do more work on UTF-8 presently. See the following post for more info: http://lemma-one.com/pipermail/proofpower_lemma-one.com/2016-February/001113.html <http://lemma-one.com/pipermail/proofpower_lemma-one.com/2016-February/001113.html> Regards, Rob.

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