In researching a question on the mailing list, I came across discussions of the question of whether {ro} has "existential import" -- which is to say, does a true proposition {ro broda cu brode} imply that {su'o broda cu brode} is also true? CLL 16.8 says:
"Lojban universal claims always imply the corresponding existential claims as well."
Which is to say, {ro} has existential import. This is the position of classic/Aristotelian logic, but not modern logic.
It was been pointed out that the documentation of negation boundaries is not consistent with this interpretation of ro. Take these examples from CLL 16.11, which are said to be equivalent:
{naku roda poi verba cu klama su'ode poi ckule} (16.11.7)
{su'oda poi verba ku'o naku klama su'ode poi ckule} (16.11.4, {ku'o}-corrected per errata)
Now let's simplify the examples, replacing the students with unicorns -- there's a tradition of talking about unicorns when considering this question:
{naku ro pavyseljirna cu blabi} == {su'o pavyseljirna naku cu blabi}
Given that {ro} has import, and assuming for the sake of argument that the universe has no unicorns to quantify, {ro pavyseljirna cu blabi} is false, and therefore, {naku ro pavyseljirna cu blabi} is true.
However, {su'o pavyseljirna naku cu blabi} is false, since there are no unicorns to predicate with {blabi}, affirmatively or negatively. The truth value of the proposition has changed despite the assurance that moving the negation boundary and "inverting" the quantifiers accordingly is supposed to preserve the meaning. Some have argued that this shows a violation of De Morgan's laws.
The anomaly does not occur if {ro} is not held to import. In that case, {ro pavyseljirna cu blabi} is true, {naku ro pavyseljirna cu blabi} is false, and {su'o pavyseljirna naku cu blabi} is also false.
This question was discussed extensively from 2002-2003, which is to say, during the BPFK's formative period. There seems to have been near-consensus that {ro} should not be held to import, but there were also emphatic dissents from John Cowan and pc.
I saw indications of an expectation that BPFK would ultimately decide the question, but I have been unable to find a record that the question was discussed or that a decision was taken.The BPFK section on "Inexact Numbers" includes a link in the "Issues" section to the 2003 discussion, but otherwise -- as far as I can discern -- takes no clear position.
Can anyone show me where and how this problem was resolved? Failing that, would anyone care to take this up and once and for all settle the matter?
mi'e la mukti mu'o