Merge pull request #438 from james-d-mitchell/fix-view-inverse-semigr…

…oups Add another ViewString method for inverse semigroups
gap-system · Jan 13, 2016 · fb86a3d · fb86a3d
2 parents c507286 + f56c5e3
commit fb86a3d
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diff --git a/lib/semigrp.gi b/lib/semigrp.gi
@@ -113,7 +113,12 @@ InstallMethod(ViewString, "for a semigroup with generators",
 InstallMethod(ViewString, "for a monoid with generators",
 [IsMonoid and HasGeneratorsOfMonoid], _ViewStringForSemigroups);
 
-InstallMethod(ViewString, "for an inverse semigroup with generators",
+InstallMethod(ViewString, "for an inverse semigroup with semigroup generators",
+[IsInverseSemigroup and HasGeneratorsOfSemigroup],
+_ViewStringForSemigroups);
+
+InstallMethod(ViewString, 
+"for an inverse semigroup with inverse semigroup generators",
 [IsInverseSemigroup and HasGeneratorsOfInverseSemigroup],
 _ViewStringForSemigroups);
 

diff --git a/tst/testinstall/semigrp.tst b/tst/testinstall/semigrp.tst
@@ -431,6 +431,19 @@ false
 gap> IsEmpty(T);
 true
 
+# Check for correct ViewString method for IsInverseSemigroup and
+# HasGeneratorsOfSemigroup
+gap> S := Semigroup(Transformation([4, 3, 5, 5, 5]),
+>                   Transformation([4, 1, 5, 2, 5]), 
+>                   Transformation([5, 5, 2, 1, 5]));
+<transformation semigroup of degree 5 with 3 generators>
+gap> IsInverseSemigroup(S);
+true
+gap> Size(S);
+36
+gap> S;
+<inverse transformation semigroup of size 36, degree 5 with 3 generators>
+
 #
 gap> STOP_TEST( "semigrp.tst", 1060000);