formal methods - How to show the “count” of a set relation? -


please have @ below

taking’ = taking  ∪  {s? → m?}

as can see, taking name relation s maps m. above relation shows adding procedure (union) adding new maptlet relation.

however, need number of s available in relation. how can it? below have done

#taking = numberofstudents

but not sure this. please help

if want know how many different student taking m (whatever m is)

it easy: need possible s taking relation , measure cardinality of resulting set.

just that:

numberofstudents = #(\dom taking)

where \dom function(relation) domain give students in relation.


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