Added simple, injective, and projective for S, I, P resp.

src/sage/quivers/path_semigroup.py

@@ -645,6 +645,8 @@ def S(self, k, vertex):
         # dimension 1 and the constructor will zero out everything else.
         return QuiverRep(k, self, {vertex: 1})
 
+    simple = S
+
     def P(self, k, vertex):
         """
         Return the indecomposable projective module over `k` at the given
@@ -683,6 +685,8 @@ def P(self, k, vertex):
             raise ValueError("must specify a valid vertex of the quiver")
         return QuiverRep(k, self, [[(vertex, vertex)]], option='paths')
 
+    projective = P
+
     def I(self, k, vertex):
         """
         Return the indecomposable injective module over `k` at the
@@ -721,6 +725,8 @@ def I(self, k, vertex):
             raise ValueError("must specify a valid vertex of the quiver")
         return QuiverRep(k, self, [[(vertex, vertex)]], option='dual paths')
 
+    injective = I
+
     def free_module(self, k):
         """
         Return a free module of rank `1` over ``kP``, where `P` is