suggested enhancements

Author: fchapoton

src/sage/combinat/cluster_algebra_quiver/cluster_seed.py

@@ -4755,14 +4755,15 @@ def coeff_recurs(p, q, a1, a2, b, c):
     """
     if p == 0 and q == 0:
         return 1
-    elif p < 0 or q < 0:
+    if p < 0 or q < 0:
         return 0
-    elif c*a1*q <= b*a2*p:
-        return sum((-1)**(k-1)*coeff_recurs(p-k, q, a1, a2, b, c)*_bino(a2-c*q+k-1, k)
-                   for k in range(1, p+1))
-    else:
-        return sum((-1)**(k-1)*coeff_recurs(p, q-k, a1, a2, b, c)*_bino(a1-b*p+k-1, k)
-                   for k in range(1, q+1))
+    if c * a1 * q <= b * a2 * p:
+        return sum((-1)**(k - 1) * coeff_recurs(p - k, q, a1, a2, b, c)
+                   *_bino(a2 - c * q + k - 1, k)
+                   for k in range(1, p + 1))
+    return sum((-1)**(k - 1) * coeff_recurs(p, q - k, a1, a2, b, c)
+               *_bino(a1 - b * p + k - 1, k)
+               for k in range(1, q + 1))
 
 
 def PathSubset(n, m):

src/sage/combinat/cluster_algebra_quiver/mutation_class.py

@@ -310,7 +310,7 @@ def _mutation_class_iter(dg, n, m, depth=infinity, return_dig6=False, show_depth
     depth_counter = 0
     if up_to_equivalence:
         iso, orbits = _dg_canonical_form(dg, mlist)
-        iso_inv = {iso[a]: a for a in iso}
+        iso_inv = {iso_a: a for a, iso_a in iso.items()}
 
     dig6 = _digraph_to_dig6(dg, hashable=True)
     dig6s = {}
@@ -346,7 +346,7 @@ def _mutation_class_iter(dg, n, m, depth=infinity, return_dig6=False, show_depth
                     if up_to_equivalence:
                         iso, orbits = _dg_canonical_form(dg_new, mlist)
                         i_new = iso[i]
-                        iso_inv = {iso[a]: a for a in iso}
+                        iso_inv = {iso_a: a for a, iso_a in iso.items()}
                     else:
                         i_new = i
                     dig6_new = _digraph_to_dig6(dg_new, hashable=True)
@@ -357,7 +357,8 @@ def _mutation_class_iter(dg, n, m, depth=infinity, return_dig6=False, show_depth
                         gets_bigger = True
                         if up_to_equivalence:
                             orbits = [orbit[0] for orbit in orbits if i_new not in orbit]
-                            iso_history = {a: dig6s[key][2][iso_inv[a]] for a in iso}
+                            d6_key = dig6s[key][2]
+                            iso_history = {a: d6_key[iso_inv[a]] for a in iso}
                             i_history = iso_history[i_new]
                             history = dig6s[key][1] + [i_history]
                             dig6s[dig6_new] = [orbits, history, iso_history]

src/sage/combinat/cluster_algebra_quiver/mutation_type.py

@@ -707,8 +707,7 @@ def _connected_mutation_type(dg):
                         return _check_special_BC_cases(dg, n, ['CD'], [None], ['D'], [[v]])
                     else:
                         return _check_special_BC_cases(dg, n, ['CD'], [None], ['D'])
-                else:
-                    return mt_tmp
+                return mt_tmp
             elif label1 == (1, -2) and label2 == (2, -1):
                 if n == 4 and (nr_same_neighbors == 2 or nr_other_neighbors == 1):
                     return QuiverMutationType(['BD', n - 1, 1])
@@ -724,35 +723,32 @@ def _connected_mutation_type(dg):
                     if nr_same_neighbors + nr_other_neighbors > 1:
                         # _reset_dg(dg, vertices, dict_in_out, [v])
                         return _check_special_BC_cases(dg, n, ['BD'], [None], ['D'], [[v]])
-                    else:
-                        return _check_special_BC_cases(dg, n, ['BD'], [None], ['D'])
+                    return _check_special_BC_cases(dg, n, ['BD'], [None], ['D'])
                 else:
                     return mt_tmp
             else:
                 return _false_return()
         elif dict_in_out[v1][2] == 1 and dict_in_out[v2][2] == 1:
             if label1 == (1, -2) and label2 == (1, -2):
                 return _check_special_BC_cases(dg, n, ['BC'], [1], ['A'])
-            elif label1 == (2, -1) and label2 == (2, -1):
+            if label1 == (2, -1) and label2 == (2, -1):
                 return _check_special_BC_cases(dg, n, ['BC'], [1], ['A'])
-            elif label1 == (1, -2) and label2 == (2, -1):
+            if label1 == (1, -2) and label2 == (2, -1):
                 return _check_special_BC_cases(dg, n, ['CC'], [1], ['A'])
-            elif label1 == (2, -1) and label2 == (1, -2):
+            if label1 == (2, -1) and label2 == (1, -2):
                 return _check_special_BC_cases(dg, n, ['BB'], [1], ['A'])
-            else:
-                return _false_return()
+            return _false_return()
         elif dict_in_out[v][0] == dict_in_out[v][1] == 1 and dict_in_out[v1][0] == dict_in_out[v1][1] == 1 and dict_in_out[v2][0] == dict_in_out[v2][1] == 1:
             _reset_dg(dg, vertices, dict_in_out, [v])
             if n == 4 and (label1, label2) == ((2, -1), (1, -2)):
                 return _check_special_BC_cases(dg, n, ['CD'], [1], ['A'])
-            elif n > 4 and (label1, label2) == ((2, -1), (1, -2)):
+            if n > 4 and (label1, label2) == ((2, -1), (1, -2)):
                 return _check_special_BC_cases(dg, n, ['CD'], [1], ['D'])
-            elif n == 4 and (label1, label2) == ((1, -2), (2, -1)):
+            if n == 4 and (label1, label2) == ((1, -2), (2, -1)):
                 return _check_special_BC_cases(dg, n, ['BD'], [1], ['A'])
-            elif n > 4 and (label1, label2) == ((1, -2), (2, -1)):
+            if n > 4 and (label1, label2) == ((1, -2), (2, -1)):
                 return _check_special_BC_cases(dg, n, ['BD'], [1], ['D'])
-            else:
-                return _false_return()
+            return _false_return()
         else:
             return _false_return()