Fix ViewString method for inverse monoids

Specifically for inverse monoids with GeneratorsOfSemigroup but not with
GeneratorsOfInverseSemigroup.  Before this commit, the method for
ViewString of an inverse monoid (with no generators) had higher
priority than the intended method.

lib/semigrp.gi

@@ -119,22 +119,27 @@ end);
 
 # ViewString
 
-InstallMethod(ViewString, "for a semigroup with generators",
+InstallMethod(ViewString, "for a semigroup with semigroup generators",
 [IsSemigroup and HasGeneratorsOfSemigroup], _ViewStringForSemigroups);
 
-InstallMethod(ViewString, "for a monoid with generators",
+InstallMethod(ViewString, "for a monoid with monoid generators",
 [IsMonoid and HasGeneratorsOfMonoid], _ViewStringForSemigroups);
 
 InstallMethod(ViewString, "for an inverse semigroup with semigroup generators",
 [IsInverseSemigroup and HasGeneratorsOfSemigroup],
 _ViewStringForSemigroups);
 
+InstallMethod(ViewString, "for an inverse monoid with semigroup generators",
+[IsInverseMonoid and HasGeneratorsOfSemigroup],
+_ViewStringForSemigroups);
+
 InstallMethod(ViewString, 
 "for an inverse semigroup with inverse semigroup generators",
 [IsInverseSemigroup and HasGeneratorsOfInverseSemigroup],
 _ViewStringForSemigroups);
 
-InstallMethod(ViewString, "for an inverse monoid with generators",
+InstallMethod(ViewString, 
+"for an inverse monoid with inverse monoid generators",
 [IsInverseMonoid and HasGeneratorsOfInverseMonoid],
 _ViewStringForSemigroups);
 

tst/testinstall/semigrp.tst

@@ -444,6 +444,18 @@ gap> Size(S);
 gap> S;
 <inverse transformation semigroup of size 36, degree 5 with 3 generators>
 
+# Check correct view method is used for inverse monoids without
+# GeneratorsOfInverseSemigroup
+gap> S := Monoid(Transformation([1, 2, 3, 4, 5, 6, 7, 7, 7]), 
+>                Transformation([4, 6, 3, 6, 6, 6, 7, 7, 7]),
+>                Transformation([4, 5, 6, 1, 6, 6, 7, 7, 7]), 
+>                Transformation([6, 6, 3, 1, 6, 6, 7, 7, 7]), 
+>                Transformation([4, 6, 6, 1, 2, 6, 7, 7, 7]));;
+gap> IsInverseSemigroup(S);
+true
+gap> S;
+<inverse transformation monoid of size 18, degree 9 with 5 generators>
+
 #
 gap> STOP_TEST( "semigrp.tst", 1090000);