From d07fc9735f40e545edda456e15dbab783c500f6a Mon Sep 17 00:00:00 2001
From: Gabriel Dos Reis <gdr@axiomatics.org>
Date: Sun, 17 Jan 2016 22:53:01 -0800
Subject: subtractIfCan$CancellationAbelianMonoid: return the more principled
 Maybe %

---
 src/algebra/idecomp.spad.pamphlet | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

(limited to 'src/algebra/idecomp.spad.pamphlet')

diff --git a/src/algebra/idecomp.spad.pamphlet b/src/algebra/idecomp.spad.pamphlet
index 51ff3a62..9e53d263 100644
--- a/src/algebra/idecomp.spad.pamphlet
+++ b/src/algebra/idecomp.spad.pamphlet
@@ -298,15 +298,16 @@ IdealDecompositionPackage(vl,nv) : C == T -- take away nv, now doesn't
        Jd:=generators(groebner J)
        not one?(#(factors factor Jd.last)) => return false
        i:=subtractIfCan(#truelist,1)
-       (i case "failed") => return true
+       (i case nothing) => return true
+       k: NNI := i
        JR:=(reverse Jd);JM:=groebnerIdeal([JR.first]);JP:List(DPoly):=[]
        for f in JR.rest repeat
-         if not ismonic(f,truelist.i) then
+         if not ismonic(f,truelist.k) then
            if not inRadical?(f,JM) then return false
            JP:=cons(f,JP)
           else
-           x:=truelist.i
-           i:=(i-1)::NNI
+           x:=truelist.k
+           k := (k-1)::NNI
 	   if not testPower(univariate(f,x),x,JM) then return false
            JM :=groebnerIdeal(append(cons(f,JP),generators JM))
        true
-- 
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