contd
f Hintikka.
He uses only one operator (which I would write here as @]) and tries
to express the various conditions for substitutivity and existence in terms
of equations !£Inr = (J with iterated modalities. I feel that this is making
the alternative relation do too much work: the fundamental condition
for substitutivity is Or = (J. The conditions involving the weaker relation
should be presented as metatheorems concerning special contexts (special
formulas <1>( T)) rather than being emphasized as part of the basic semantics.
It seems to me that the present approach provides quite a suitable place
for #Hintikka's useful and important insights