minor liftabale changes

pzinn · Oct 7, 2024 · 309161a · 309161a
1 parent 28bee55
commit 309161a
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Showing 4 changed files with 4 additions and 4 deletions.
diff --git a/M2/Macaulay2/m2/quotring.m2 b/M2/Macaulay2/m2/quotring.m2
@@ -281,7 +281,7 @@ char QuotientRing := (stashValue symbol char) ((S) -> (
      g := generators gb relns;
      if g == 0 then return char ring g;
      m := g_(0,0);
-     if liftable(m,ZZ) then lift(m,ZZ) else 0))
+     lift(m,ZZ,Verify=>false) ?? 0))
 
 singularLocus = method()
 singularLocus(Ring) := QuotientRing => (R) -> (

diff --git a/M2/Macaulay2/m2/rationals.m2 b/M2/Macaulay2/m2/rationals.m2
@@ -50,7 +50,6 @@ assert (hash ZZ < hash QQ)
 lift(QQ,ZZ) := opts -> (r,o) -> if denominator r === 1 then numerator r else if opts.Verify then error "rational number is not an integer"
 liftable(QQ,ZZ) := (r,o) -> denominator r === 1
 lift(QQ,QQ) := opts -> (r,QQ) -> r
-liftable(QQ,QQ) := (QQ,QQ) -> true
 
 QQ.degreeLength = 0
 isUnit Number := x -> x != 0

diff --git a/M2/Macaulay2/m2/rings.m2 b/M2/Macaulay2/m2/rings.m2
@@ -90,12 +90,13 @@ toExternalString Ring := toString @@ describe
 -- promote, lift, liftable, and isConstant
 -----------------------------------------------------------------------------
 
+-- TODO rename isLiftable; currently impossible due to conflict with Varieties::isLiftable
 -- some remnants from lift and promote, version 2
 liftable = method(TypicalValue => Boolean, Dispatch => {Thing, Type, Type})
 liftable(Number,      Number)      :=
 liftable(Number,      RingElement) :=
 liftable(RingElement, Number)      :=
-liftable(RingElement, RingElement) := (f, R) -> null =!= lift(f, R, Verify => false)
+liftable(RingElement, RingElement) := (f, R) -> lookup(lift,class f,R) =!= null and null =!= lift(f, R, Verify => false)
 
 isConstant = method(TypicalValue => Boolean)
 isConstant RingElement := r -> liftable(r, coefficientRing ring r)

diff --git a/M2/Macaulay2/packages/Macaulay2Doc/functions/liftable-doc.m2 b/M2/Macaulay2/packages/Macaulay2Doc/functions/liftable-doc.m2
@@ -6,7 +6,7 @@
 
 undocumented {(liftable, Number, Number), (liftable, Number, RingElement), 
      (liftable, RingElement, Number), (liftable, RingElement, RingElement),
-     (liftable, QQ, QQ), (liftable, QQ, ZZ),
+     (liftable, QQ, ZZ),
      (lift, Matrix, InexactNumber),
      (lift,Matrix,InexactNumber'),(lift, Number, InexactNumber),
      (liftable, Number, InexactNumber),