This function creates an object of type CurveClassRepresentativeM0nbar from a hash table. Here is a basic example:
i1 : H1=new HashTable from { {{{1,2},{3},{4},{5}},1}, {{{1,3},{2},{4},{5}},1} };
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i2 : curveClassRepresentativeM0nbar(5,H1)
o2 = CurveClassRepresentativeM0nbar{CurveExpression => HashTable{{{1, 2}, {3}, {4}, {5}} => 1}}
{{1, 3}, {2}, {4}, {5}} => 1
NumberOfMarkedPoints => 5
o2 : CurveClassRepresentativeM0nbar
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Warning: when you enter a hash table in Macaulay2, if you use a key more than once, the first instance is discarded. Here is an example where the behavior may differ from what you want:
i3 : H=new HashTable from { {{{1,2},{3},{4},{5}},1}, {{{1,3},{2},{4},{5}},1}, {{{1,2},{3},{4},{5}},2}}
o3 = HashTable{{{1, 2}, {3}, {4}, {5}} => 2}
{{1, 3}, {2}, {4}, {5}} => 1
o3 : HashTable
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The user probably wanted $F_{\{1,2\},\{3\},\{4\},\{5\}} + 2F_{\{1,2\},\{3\},\{4\},\{5\}}$ to give $3F_{\{1,2\},\{3\},\{4\},\{5\}}$ instead. So if your expression has two terms that are written exactly alike, you could either combine them before you create the input hash table, or input a list instead.
i4 : L= { {{{1,2},{3},{4},{5}},1}, {{{1,3},{2},{4},{5}},1}, {{{1,2},{3},{4},{5}},2}}
o4 = {{{{1, 2}, {3}, {4}, {5}}, 1}, {{{1, 3}, {2}, {4}, {5}}, 1}, {{{1, 2}, {3}, {4}, {5}}, 2}}
o4 : List
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i5 : curveClassRepresentativeM0nbar(5,L)
o5 = CurveClassRepresentativeM0nbar{CurveExpression => HashTable{{{1, 2}, {3}, {4}, {5}} => 3}}
{{1, 3}, {2}, {4}, {5}} => 1
NumberOfMarkedPoints => 5
o5 : CurveClassRepresentativeM0nbar
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For this reason, most users will probably prefer to enter curves via lists, rather than hash tables.
The function curveClassRepresentative does the same minimal testing if you enter a hash table that it does if you enter a list. See the documentation for curveClassRepresentativeM0nbar(ZZ,List).