From 6b3e0bd256f3164a67e8d5ddd4e8c3bfc5a98104 Mon Sep 17 00:00:00 2001
From: Doug Torrance <dtorrance@piedmont.edu>
Date: Fri, 24 May 2024 08:51:39 -0400
Subject: [PATCH 1/2] Refactor dedupSymbols to allow more than two duplicates

Closes: #3261
---
 M2/Macaulay2/m2/monoids.m2 | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/M2/Macaulay2/m2/monoids.m2 b/M2/Macaulay2/m2/monoids.m2
index e3d85493237..aea587f6b50 100644
--- a/M2/Macaulay2/m2/monoids.m2
+++ b/M2/Macaulay2/m2/monoids.m2
@@ -474,14 +474,22 @@ checkSymbol = sym -> if instance(sym, Symbol) or lookup(symbol <-, class sym) =!
 -- turns {x, y, z, y} into {x, y_0, z, y_1}
 -- adding 'toString' in a few places will eliminate more duplications
 -- but makes creating temporary rings in functions more difficult.
-dedupSymbols = varlist -> if 0 == repeats varlist then varlist else while 0 < repeats varlist do (
-    mapping := hashTable toList pairs varlist;
-    -- TODO: applyPairs with collision handler, and accepting MutableHashTable
-    counter := new MutableHashTable from applyKeys(mapping,
-	i -> varlist#i, dups -> makeVars(#dups, first dups));
-    varlist = values applyValues(mapping, var -> if instance(counter#(name := var), List)
-	then first(counter#name#0, counter#name = drop(counter#name, 1)) else var);
-    if 0 == repeats varlist then break varlist else varlist)
+dedupSymbols = varlist -> (
+    while repeats varlist > 0 do (
+	counts := tally varlist;
+	data := hashTable apply(keys counts,
+	    var -> (
+		var,
+		new MutableList from {
+		    0,
+		    if counts#var > 1 then (
+			makeVars(counts#var, var))
+		    else {var}}));
+	varlist = apply(varlist, var -> (
+		newvar := data#var#1#(data#var#0);
+		data#var#0 += 1;
+		newvar)));
+    varlist)
 
 -- also used in AssociativeAlgebras.m2
 findSymbols = varlist -> dedupSymbols toList apply(pairs listSplice varlist,

From 4ea15ca1b524f51a3541ac97e70a96110cedc4eb Mon Sep 17 00:00:00 2001
From: Doug Torrance <dtorrance@piedmont.edu>
Date: Fri, 24 May 2024 08:54:55 -0400
Subject: [PATCH 2/2] Add unit test for variable deduplication w/ 3 duplicates

---
 M2/Macaulay2/tests/normal/monoids.m2 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/M2/Macaulay2/tests/normal/monoids.m2 b/M2/Macaulay2/tests/normal/monoids.m2
index 103f465e01e..29ff62a141b 100644
--- a/M2/Macaulay2/tests/normal/monoids.m2
+++ b/M2/Macaulay2/tests/normal/monoids.m2
@@ -230,6 +230,7 @@ assert(gens(B = A ** A) == {x_0,y_0,x_1,y_1}) -- TODO: eliminate the warning
 assert(gens(C = B ** B) == {x_(0,0),y_(0,0),x_(0,1),y_(0,1),x_(1,0),y_(1,0),x_(1,1),y_(1,1)})
 assert(toString gens(A ** B) == "{x, y, x_0, y_0, x_1, y_1}") -- TODO: not yet working without toString
 assert(toString gens(monoid[x,y,x,z]) == "{x_0, y, x_1, z}") -- TODO: not yet working without toString
+assert(toString gens(monoid[x,x,x]) == "{x_0, x_1, x_2}") -- issue #3261
 
 -- test ^** and runLengthEncode
 -- TODO: what should happen for odd powers?