A problem of Rosser and Turquette
Angelo Margaris · Journal of Symbolic Logic · 1958
In this paper an affirmative solution is given for the following problem in many-valued logic posed by Rosser and Turquette in [6] p. 110: For every triple ‹s, t, m› with 1 ≤ s t is provable. III. Of those statements which always take values ≤ t and sometimes take a value > s, some are provable and some are not. We state now, temporarily deferring comment, a more demanding alternative to Condition III: III′. For every truth value k such that s k, and P is provable and Q is not. In § 2 a solution is given on the level of the statement calculus. The remainder of the present section is devoted to some negative results which serve to clarify the problem, and one positive result which shall cause us to replace Condition III by III′. We confine our attention to the statement calculus.