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4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / f. System B

[version imposing two conditions on accessibility]

5 ideas
In B it seems logically possible to have both p true and p is necessarily possibly false [Salmon,N]
System B has not been justified as fallacy-free for reasoning on what might have been [Salmon,N]
System B implies that possibly-being-realized is an essential property of the world [Salmon,N]
The system B has the 'reflexive' and 'symmetric' conditions on its accessibility relation [Fitting/Mendelsohn]
System B introduces iterated modalities [Sider]