When the option is used with the function randomMonomialIdeals, if IncludeZeroIdeals => true (the default), then zero ideals will be included in the list of random monomial ideals. If IncludeZeroIdeals => false, then any zero ideals produced will be excluded, along with the number of them.
i1 : n=2;D=2;p=0.0;N=1; |
i5 : ideals = randomMonomialIdeals(n,D,p,N) o5 = {monomialIdeal ()} o5 : List |
The 0 listed is the zero ideal:
i6 : ideals_0 o6 = monomialIdeal () o6 : MonomialIdeal of QQ[x ..x ] 1 2 |
In the example below, in contrast, the list of ideals returned is empty since the single zero ideal generated is excluded:
i7 : randomMonomialIdeals(n,D,p,N,IncludeZeroIdeals=>false) o7 = ({}, 1) o7 : Sequence |
The option can also be used with the function bettiStats. If ideals contains zero ideals, you may wish to exclude them when computing the Betti table statistics. In this case, use the optional input as follows:
i8 : R=ZZ/101[a..c] o8 = R o8 : PolynomialRing |
i9 : L={monomialIdeal (a^2*b,b*c), monomialIdeal(a*b,b*c^3),monomialIdeal 0_R}; |
i10 : apply(L,i->betti res i) 0 1 2 0 1 2 0 o10 = {total: 1 2 1, total: 1 2 1, total: 1} 0: 1 . . 0: 1 . . 0: 1 1: . 1 . 1: . 1 . 2: . 1 1 2: . . . 3: . 1 1 o10 : List |
i11 : bettiStats(L,IncludeZeroIdeals=>false) The Betti statistics do not include those for the zero ideals. 0 1 2 0 1 2 1 2 o11 = (total: 1 2 1, total: 1 2 1, total: 1 1) 0: 1 . . 0: 1 . . 2: .5 .5 1: . 1 . 1: . 1 . 3: .5 .5 2: . .5 .5 2: . .5 .5 3: . .5 .5 3: . .5 .5 o11 : Sequence |
i12 : bettiStats(L,IncludeZeroIdeals=>false,Verbose=>true) There are 3 ideals in this sample. Of those, 1 are the zero ideal. The Betti statistics do not include those for the zero ideals. 0 1 2 0 1 2 1 2 o12 = (total: 1 2 1, total: 1 2 1, total: 1 1) 0: 1 . . 0: 1 . . 2: .5 .5 1: . 1 . 1: . 1 . 3: .5 .5 2: . .5 .5 2: . .5 .5 3: . .5 .5 3: . .5 .5 o12 : Sequence |
The object IncludeZeroIdeals is a symbol.