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Consider the definition of a constraint C containing a propagating
indexical X in R
. Let TV(X,C,S) denote the set
of values for X that can make C true in some ground
extension of the store S. Then the indexical should obey the
following coding rules:
If the coding rules are observed, then S(R) can be proven to contain
TV(X,C,S) for all stores in which R is monotone. Hence it
is natural for the implementation to wait until R becomes monotone
before admitting the propagating indexical for execution. The execution
of X in R
thus involves the following:
A propagating indexical is scheduled for execution as follows:
dom(Y)
or card(Y)
in R has been updated
min(Y)
in R has been updated
max(Y)
in R has been updated