diff --git a/docs/base-logic.tex b/docs/base-logic.tex index 6c8782d14a6d19b805071817cc77a0582f1acfba..f0b97ad9c950ade18eae79cfd362e1052dca58d4 100644 --- a/docs/base-logic.tex +++ b/docs/base-logic.tex @@ -432,13 +432,14 @@ The premise in \ruleref{upd-update} is a \emph{meta-level} side-condition that h The consistency statement of the logic reads as follows: For any $n$, we have \begin{align*} - \lnot(\TRUE \proves (\upd\later)^n\spac\FALSE) + \lnot(\TRUE \proves (\later)^n\spac\FALSE) \end{align*} -where $(\upd\later)^n$ is short for $\upd\later$ being nested $n$ times. +where $(\later)^n$ is short for $\later$ being nested $n$ times. The reason we want a stronger consistency than the usual $\lnot(\TRUE \proves \FALSE)$ is our modalities: it should be impossible to derive a contradiction below the modalities. -For $\always$, this follows from the elimination rule, but the other two modalities do not have an elimination rule. -Hence we declare that it is impossible to derive a contradiction below any combination of these two modalities. +For $\always$ and $\plainly$, this follows from the elimination rules. +For updates, we use the fact that $\upd\FALSE \proves \upd\plainly\FALSE \proves \FALSE$. +However, there is no elimination rule for $\later$, so we declare that it is impossible to derive a contradiction below any number of laters. %%% Local Variables: