isEffectiveExpression -- determines whether a curve class expression is effective

Synopsis

Usage:

isEffectiveExpression(C)
Inputs:
- C, an instance of the type CurveClassRepresentativeM0nbar,
Outputs:
- a Boolean value,

Description

This function tests whether the coefficients in an object of type CurveClassRepresentativeM0nbar are all nonnegative.

Warning: this function tests only the input representative of a curve class. That is, it answers whether the input is an effective expression, not whether there exists an effective expression equivalent to the input.

i1 : L1= { {{{2,1},{3},{4},{5}},-2}, {{{1,3},{2},{4},{5}},-7}, {{{1,4},{2},{3},{5}},1}};

i2 : C1=curveClassRepresentativeM0nbar(5,L1);

i3 : isEffectiveExpression(C1)

o3 = false

i4 : L2={ {{{2,1},{3},{4},{5}},2}, {{{1,3},{2},{4},{5}},7}, {{{1,4},{2},{3},{5}},1}};

i5 : C2=curveClassRepresentativeM0nbar(5,L2);

i6 : isEffectiveExpression(C2)

o6 = true

Ways to use isEffectiveExpression :

isEffectiveExpression(CurveClassRepresentativeM0nbar)
isEffectiveExpression(DivisorClassRepresentativeM0nbar) -- determines whether a divisor class expression is effective

For the programmer

The object isEffectiveExpression is a method function.