Let $L =\{k_1,\dots,k_m\}$ be a set of ranks of linear subscpaces of $\mathbb C^n$ and consider a subset $L' \subseteq L$. Let $X = Fl(L; n)$ and $Y=Fl(L';n)$ be the associated generalized flag varieties (if they exist). This method produces the canonical projection from $X$ to $Y$ that forgets the linear subspaces having ranks $L \setminus L'$.
i1 : R = makeCharacterRing 3 o1 = R o1 : PolynomialRing |
i2 : X = generalizedFlagVariety("B",3,{1,2},R);
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i3 : Y1 = generalizedFlagVariety("B",3,{2},R);
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i4 : Y2 = generalizedFlagVariety("B",3,{1},R);
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i5 : peek flagMap(X,Y1)
o5 = EquivariantMap{cache => CacheTable{} }
ptsMap => HashTable{{set {0*}, set {0*, 1*}} => {set {0*, 1*}}}
{set {0*}, set {0*, 1}} => {set {0*, 1}}
{set {0*}, set {0*, 2*}} => {set {0*, 2*}}
{set {0*}, set {0*, 2}} => {set {0*, 2}}
{set {0}, set {0, 1*}} => {set {0, 1*}}
{set {0}, set {0, 1}} => {set {0, 1}}
{set {0}, set {0, 2*}} => {set {0, 2*}}
{set {0}, set {0, 2}} => {set {0, 2}}
{set {1*}, set {0*, 1*}} => {set {0*, 1*}}
{set {1*}, set {0, 1*}} => {set {0, 1*}}
{set {1*}, set {1*, 2*}} => {set {1*, 2*}}
{set {1*}, set {1*, 2}} => {set {1*, 2}}
{set {1}, set {0*, 1}} => {set {0*, 1}}
{set {1}, set {0, 1}} => {set {0, 1}}
{set {1}, set {1, 2*}} => {set {1, 2*}}
{set {1}, set {1, 2}} => {set {1, 2}}
{set {2*}, set {0*, 2*}} => {set {0*, 2*}}
{set {2*}, set {0, 2*}} => {set {0, 2*}}
{set {2*}, set {1*, 2*}} => {set {1*, 2*}}
{set {2*}, set {1, 2*}} => {set {1, 2*}}
{set {2}, set {0*, 2}} => {set {0*, 2}}
{set {2}, set {0, 2}} => {set {0, 2}}
{set {2}, set {1*, 2}} => {set {1*, 2}}
{set {2}, set {1, 2}} => {set {1, 2}}
source => a GKM variety with an action of a 3-dimensional torus
target => a GKM variety with an action of a 3-dimensional torus
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i6 : peek flagMap(X,Y2)
o6 = EquivariantMap{cache => CacheTable{} }
ptsMap => HashTable{{set {0*}, set {0*, 1*}} => {set {0*}}}
{set {0*}, set {0*, 1}} => {set {0*}}
{set {0*}, set {0*, 2*}} => {set {0*}}
{set {0*}, set {0*, 2}} => {set {0*}}
{set {0}, set {0, 1*}} => {set {0}}
{set {0}, set {0, 1}} => {set {0}}
{set {0}, set {0, 2*}} => {set {0}}
{set {0}, set {0, 2}} => {set {0}}
{set {1*}, set {0*, 1*}} => {set {1*}}
{set {1*}, set {0, 1*}} => {set {1*}}
{set {1*}, set {1*, 2*}} => {set {1*}}
{set {1*}, set {1*, 2}} => {set {1*}}
{set {1}, set {0*, 1}} => {set {1}}
{set {1}, set {0, 1}} => {set {1}}
{set {1}, set {1, 2*}} => {set {1}}
{set {1}, set {1, 2}} => {set {1}}
{set {2*}, set {0*, 2*}} => {set {2*}}
{set {2*}, set {0, 2*}} => {set {2*}}
{set {2*}, set {1*, 2*}} => {set {2*}}
{set {2*}, set {1, 2*}} => {set {2*}}
{set {2}, set {0*, 2}} => {set {2}}
{set {2}, set {0, 2}} => {set {2}}
{set {2}, set {1*, 2}} => {set {2}}
{set {2}, set {1, 2}} => {set {2}}
source => a GKM variety with an action of a 3-dimensional torus
target => a GKM variety with an action of a 3-dimensional torus
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The object flagMap is a method function.