This chapter describes boolean lists. A boolean list is a list that
has no holes and contains only the boolean values true and false
(see Chapter Booleans).
In function names we call boolean lists blist for brevity.
IsBlist( obj ) C
A boolean list (``blist'') is a list that has no holes and contains only
true and false. If a list is known to be a boolean list by a test
with IsBlist it is stored in a compact form. See More about Boolean Lists.
gap> IsBlist( [ true, true, false, false ] ); true gap> IsBlist( [] ); true gap> IsBlist( [false,,true] ); false # has holes gap> IsBlist( [1,1,0,0] ); false # contains not only boolean values gap> IsBlist( 17 ); false # is not even a list
Boolean lists are lists and all operations for lists are therefore applicable to boolean lists.
Boolean lists can be used in various ways, but maybe the most important
application is their use for the description of subsets of finite sets.
Suppose set is a finite set, represented as a list. Then a subset
sub of set is represented by a boolean list blist of the same
length as set such that blist[i] is true if set[i] is in
sub and false otherwise.
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GAP 4 manual