diff --git a/src/analysis/typepal/Solver.rsc b/src/analysis/typepal/Solver.rsc
index e5bfe24..fe35ba4 100644
--- a/src/analysis/typepal/Solver.rsc
+++ b/src/analysis/typepal/Solver.rsc
@@ -3,21 +3,22 @@ module analysis::typepal::Solver
 /*
     Implementation of the ISolver interface; this is the API of TypePal's constraint solver
 */
-import Set;
-import Node;
-import Map;
+extend analysis::typepal::Collector;
+extend analysis::typepal::Messenger;
+
+import Exception;
 import IO;
 import List;
 import Location;
+import Map;
+import Message;
+import Node;
 import ParseTree;
-import Type;
+import Set;
 import String;
-import Message;
-import Exception;
-//import util::Benchmark;
-
-extend analysis::typepal::Collector;
-extend analysis::typepal::Messenger;
+import Type;
+import analysis::typepal::StringSimilarity;
+import util::IDEServices;
 
 void checkAllTypesAvailable(TModel tm){
     for(tup: <loc _, str _, str _, IdRole _, loc _, DefInfo defInfo> <- tm.defines){
@@ -1517,13 +1518,13 @@ Solver newSolver(map[str,Tree] namedTrees, TModel tm){
                  foundDefs = scopeGraph.lookup(u);
              } catch NoBinding(): {
                 roles = size(u.idRoles) > 5 ? "" : intercalateOr([prettyRole(idRole) | idRole <- u.idRoles]);
-                messages += error("Undefined <roles> `<getOrgId(u)>`", u.occ);
+                messages += error("Undefined <roles> `<getOrgId(u)>`", u.occ, fixes=undefinedNameProposals(u, tm));
              }
         }
 
         for(u <- notYetDefinedUses){
             roles = size(u.idRoles) > 5 ? "" : intercalateOr([prettyRole(idRole) | idRole <- u.idRoles]);
-            messages += error("Undefined <roles> `<getOrgId(u)>`", u.occ);
+            messages += error("Undefined <roles> `<getOrgId(u)>`", u.occ, fixes=undefinedNameProposals(u, tm));
         }
 
         error_locations = { src | error(_,loc src) <- messages };
@@ -1704,3 +1705,14 @@ Solver newSolver(map[str,Tree] namedTrees, TModel tm){
 
     return thisSolver;
 }
+
+// CodeActions for errors generated by Solver
+
+list[CodeAction] undefinedNameProposals(Use u, TModel tm)
+    =
+    [ action(
+        title="Replace undefined `<getOrgId(u)>`", 
+        edits=[changed([replace(u.occ, prop)])]
+      )
+    | str prop <- similarNames(getOrgId(u), u.idRoles, tm, 3)
+    ];
\ No newline at end of file
diff --git a/src/analysis/typepal/StringSimilarity.rsc b/src/analysis/typepal/StringSimilarity.rsc
index 12de519..afd3866 100644
--- a/src/analysis/typepal/StringSimilarity.rsc
+++ b/src/analysis/typepal/StringSimilarity.rsc
@@ -1,41 +1,37 @@
 module analysis::typepal::StringSimilarity
 
-import String;
 import List;
+import String;
+import analysis::typepal::TModel;
 
+@synopsis{Tryadic minimum function on integers}
 int min(int a, int b, int c)
 =   a < b ? (a < c ? a : c) : (b < c ? b : c);
 
 @synopsis{Calculate the Levenshtein distance of 2 strings}
-@memo
-int lev(str a, str b)
-    = lev(a, 0, b, 0);
-
-@memo
-private int lev(str a, int ia, str b, int ib){
-    if(ib == size(b)) return size(a) - ia;
-    if(ia == size(a)) return size(b) - ib;
-    if(a[ia] == b[ib]) return lev(a, ia+1, b, ib+1);
-
-    return 1 + min(lev(a, ia+1, b, ib),
-                   lev(a, ia,   b, ib+1),
-                   lev(a, ia+1, b, ib+1));
+int lev(str a, str b){
+    int sizea = size(a);
+    int sizeb = size(b);
+
+    @memo
+    int lev(int ia, int ib){
+        if(ib == sizeb) return sizea - ia;
+        if(ia == sizea) return sizeb - ib;
+        if(a[ia] == b[ib]) return lev(ia+1, ib+1);
+
+        return 1 + min(lev(ia+1, ib),
+                       lev(ia,   ib+1),
+                       lev(ia+1, ib+1));
+    }
+
+    return  lev(0, 0);
 }
 
-// @memo
-// private int lev(str a, int ia, int lena, str b, int ib, int lenb){
-//     if(lenb == 0) return lena;
-//     if(lena == 0) return lenb;
-//     if(a[ia] == b[ib]) return lev(a, ia+1, lena-1, b, ib+1, lenb-1);
+// Tests for `lev`
 
-//     return 1 + min(lev(a, ia+1, lena-1, b, ib,   lenb),
-//                    lev(a, ia,   lena,   b, ib+1, lenb-1),
-//                    lev(a, ia+1, lena-1, b, ib+1, lenb-1));
-// }
+test bool levCommutative(str a, str b) = lev(a, b) == lev(b, a);
 
-test bool lev0(str a, str b) = lev(a, b) == lev(b, a);
-
-test bool levx(str a, str b, str c) = lev(a, b) == lev(c + a, c + b);
+test bool levLeftAdditive(str a, str b, str c) = lev(a, b) == lev(c + a, c + b);
 
 test bool lev1() = lev("kitten", "sitting") == 3;
 test bool lev2() = lev("kelm", "hello") == 3;
@@ -47,10 +43,17 @@ test bool lev7() = lev("page", "pope") == 2;
 test bool lev8() = lev("december", "january") == 8;
 test bool lev9() = lev("march", "may") == 3;
 
+// Similarity functions to be used by TypePal
 
+@synopsis{WordSim represents one word from the vocabulary and its similariy to the original word}
 alias WordSim = tuple[str word, int sim];
 
+@synopsis{Compute list of words from vocabulary, that are similar to give word w with at most maxDistance edits}
 list[str] similarWords(str w, list[str] vocabulary, int maxDistance)
 = sort([ <v, d> | str v <- vocabulary, d := lev(w, v), d <= maxDistance ], bool (WordSim x, WordSim y){ return x.sim < y.sim;}).word;
 
-value main() = similarWords("ac", ["a", "ab", "ac", "x"], 10);
\ No newline at end of file
+@synopsis{Find in TModel tm, names similar to w, in gives roles, with at most maxDistance edits}
+list[str] similarNames(str w, set[IdRole] idRoles, TModel tm, int maxDistance){
+    vocabulary = [ d.orgId | d <- tm.defines, d.idRole in idRoles ];
+    return similarWords(w, vocabulary, maxDistance);
+}