Implemented base locus ideal of toric linear series

Macaulay2 · Jun 2, 2024 · 51a1f8e · 51a1f8e
1 parent 36b0950
commit 51a1f8e
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Showing 3 changed files with 22 additions and 1 deletion.
diff --git a/ToricExtras.m2 b/ToricExtras.m2
@@ -55,7 +55,8 @@ newPackage(
 
 export {
     "ToricLinearSeries",
-    "toricLinearSeries"
+    "toricLinearSeries",
+    "baseLocusIdeal"
     }
 
 

diff --git a/ToricExtras/ToricLinearSeries.m2 b/ToricExtras/ToricLinearSeries.m2
@@ -34,6 +34,11 @@ isComplete ToricLinearSeries := linSeries -> (
     setM == set degDMonomials
 )
 
+baseLocusIdeal = method(TypicalValue => Ideal)
+
+baseLocusIdeal ToricLinearSeries := linSeries -> (
+    ideal monomials linSeries
+)
 
 -- -- helper for listing monomials of given degree in the ring
 -- -- TODO: move to Core

diff --git a/ToricExtras/ToricLinearSeriesTests.m2 b/ToricExtras/ToricLinearSeriesTests.m2
@@ -29,4 +29,19 @@ TEST ///
     assert not isComplete M3;
     assert not isComplete M4;
     assert isComplete M5;
+///
+
+TEST ///
+    P2 = toricProjectiveSpace 2;
+    S = ring P2;
+    M1 = toricLinearSeries flatten entries basis(1,S);
+    M2 = toricLinearSeries {x_0};
+    M3 = toricLinearSeries {x_0, x_0, x_0};
+    M4 = toricLinearSeries {x_0, x_1, x_2, x_2};
+    M5 = toricLinearSeries {x_2, x_1, x_0};
+    assert (baseLocusIdeal M1 == ideal(x_0, x_1, x_2));
+    assert (baseLocusIdeal M2 == ideal(x_0));
+    assert (baseLocusIdeal M3 == ideal(x_0));
+    assert (baseLocusIdeal M4 == ideal(x_0, x_1, x_2));
+    assert (baseLocusIdeal M5 == ideal(x_0, x_1, x_2));
 ///