diff --git a/dev/DTcodes.py b/dev/DTcodes.py
index f6af208..bd98f39 100644
--- a/dev/DTcodes.py
+++ b/dev/DTcodes.py
@@ -121,7 +121,7 @@ def upper_pair(self):
         return (0,2) if bool(first % 2) ^ even_over else (1,3)
 
 
-class DTPath():
+class DTPath:
     """
     An iterator which starts at a FatEdge and walks around the
     link component containing that edge.  A DTPath raises
@@ -215,7 +215,7 @@ def clear(self):
         """
         for e in self.edges:
             e.marked = False
-        self.marked_valences = dict( (v,0) for v in self.vertices )
+        self.marked_valences = { v: 0 for v in self.vertices }
 
     def push(self, flips):
         """
@@ -283,7 +283,7 @@ def marked_arc(self, vertex):
         left_path, right_path, vertices = [], [], set()
         vertices.add(vertex)
         try:
-            left, right = [e for e in self(vertex) if e.marked]
+            left, right = (e for e in self(vertex) if e.marked)
         except ValueError:
             raise RuntimeError('Vertex must have two marked edges.')
         for edge, path in (left, left_path), (right, right_path):
@@ -533,7 +533,7 @@ def KLP_dict(self, vertex, indices):
 # This assumes that the diagram has no loops, and that each component
 # meets the next one (so in particular the diagram is connected.
 
-class DTcodec():
+class DTcodec:
     """
     Codec for DT codes of a link projection.
     """
@@ -871,7 +871,7 @@ def KLPProjection(self):
         vertices = list(G.vertices)
         num_crossings = len(vertices)
         num_components = len(self.code)
-        KLP_indices = dict( (v,n) for n, v in enumerate(vertices))
+        KLP_indices = { v: n for n, v in enumerate(vertices)}
         KLP_crossings = [G.KLP_dict(v, KLP_indices) for v in vertices]
         return len(G.vertices), 0, len(self.code), KLP_crossings
 
diff --git a/dev/dev_jennet/bridge_finding.py b/dev/dev_jennet/bridge_finding.py
index 14a66c5..eb46112 100644
--- a/dev/dev_jennet/bridge_finding.py
+++ b/dev/dev_jennet/bridge_finding.py
@@ -15,8 +15,8 @@ def find_bridges(G):
     bridges = []
 
     verts = G.vertices()
-    low = dict([(v,-1) for v in verts])
-    preorder = dict([(v,-1) for v in verts])
+    low = {v: -1 for v in verts}
+    preorder = {v: -1 for v in verts}
 
     for v in verts:
         if preorder[v] == -1:
diff --git a/dev/dev_malik/fast_jones_patch.py b/dev/dev_malik/fast_jones_patch.py
index 3279904..fb1d5a8 100644
--- a/dev/dev_malik/fast_jones_patch.py
+++ b/dev/dev_malik/fast_jones_patch.py
@@ -106,7 +106,7 @@ def simplify_monomial(monomial):
 #        monomial = remove_squares(monomial)
 #        monomial = remove_loops(monomial)
 
-        strand_vars = monomial.free_symbols - set([A])
+        strand_vars = monomial.free_symbols - {A}
         strand_labels = all_labels(strand_vars)
 
     return monomial
@@ -129,7 +129,7 @@ def combine_strands(v1, v2, common_label):
 
 def remove_squares(monomial):
     A, B = sympy.symbols('A,B')
-    strand_vars = monomial.free_symbols - set([A,B])
+    strand_vars = monomial.free_symbols - {A,B}
     for v in strand_vars:
         monomial = monomial.subs(v*v,-A**2-(1/A)**2)
     return monomial
@@ -137,7 +137,7 @@ def remove_squares(monomial):
 
 def remove_loops(monomial):
     A, B = sympy.symbols('A,B')
-    strand_vars = monomial.free_symbols - set([A,B])
+    strand_vars = monomial.free_symbols - {A,B}
     for v in strand_vars:
         l1, l2 = var_to_strand_labels(v)
         if l1 == l2:
diff --git a/dev/dev_malik/mutation/tangle_patch.py b/dev/dev_malik/mutation/tangle_patch.py
index 3828fcc..97fb2a4 100644
--- a/dev/dev_malik/mutation/tangle_patch.py
+++ b/dev/dev_malik/mutation/tangle_patch.py
@@ -356,7 +356,7 @@ def all_cross_strands(self):
                 other_ends_seen.append(end)
     orientations, over_or_under = crossing_orientations(strands)
     cs_seen = [cs for strand in strands for cs in strand]
-    seen_once = set(cs[0] for cs in cs_seen)
+    seen_once = {cs[0] for cs in cs_seen}
     for crossing in orientations:
         seen_once.remove(crossing)
     for strand in strands:
@@ -873,7 +873,7 @@ def tangle_cut(link, cycle):
 def fill_in_crossings(link,sides):
     crossing_sides = {x[0]:sides[x] for x in sides}
     crossing_labels = map(lambda c: c.label,link.crossings)
-    crossings_to_sort = set(crossing_labels)-set(x[0] for x in sides)
+    crossings_to_sort = set(crossing_labels)-{x[0] for x in sides}
     while len(crossings_to_sort) > 0:
         start_crossing = crossings_to_sort.pop()
         accumulated_crossings = [start_crossing]
@@ -1158,7 +1158,7 @@ def close_float_sets(L1, L2, tolerance):
 print(v,avg_vol)
 """
 
-a, b, c, d, e, f, g, h = [spherogram.Crossing(x) for x in 'abcdefgh']
+a, b, c, d, e, f, g, h = (spherogram.Crossing(x) for x in 'abcdefgh')
 a[0] = e[2]
 a[1] = b[3]
 a[3] = e[3]
diff --git a/dev/dev_malik/thompson/graphknotter.py b/dev/dev_malik/thompson/graphknotter.py
index c1ea2cd..6d4a8fd 100644
--- a/dev/dev_malik/thompson/graphknotter.py
+++ b/dev/dev_malik/thompson/graphknotter.py
@@ -170,8 +170,8 @@ def edge_to_str_pair(edge):
 
 
 def doubled_edge_to_str_pair(e):
-    s1 = set([e[0].split()[0].split('\'')[1], e[0].split()[1].split('\'')[1]])
-    s2 = set([e[1].split()[0].split('\'')[1], e[1].split()[1].split('\'')[1]])
+    s1 = {e[0].split()[0].split('\'')[1], e[0].split()[1].split('\'')[1]}
+    s2 = {e[1].split()[0].split('\'')[1], e[1].split()[1].split('\'')[1]}
     return [s1,s2]
 
 def simple_cut(link, cs1, cs2):
diff --git a/dev/dev_malik/unknotting_number.py b/dev/dev_malik/unknotting_number.py
index dce6f38..c883a2c 100644
--- a/dev/dev_malik/unknotting_number.py
+++ b/dev/dev_malik/unknotting_number.py
@@ -6,7 +6,7 @@
 def doubly_connected_crossing(link):
     doubly_connected = None
     for c in link.crossings:
-        num_neighbors = len(set(x[0] for x in c.adjacent))
+        num_neighbors = len({x[0] for x in c.adjacent})
         if num_neighbors == 2:
             return c
         elif num_neighbors == 3:
diff --git a/dev/dt_issue.py b/dev/dt_issue.py
index fb6ecca..39d48d4 100644
--- a/dev/dt_issue.py
+++ b/dev/dt_issue.py
@@ -64,4 +64,4 @@ def fill_vols(M):
 
 def plink_component_order_test(N):
     M2 = snappy.Manifold()
-    return set(test_DT(dt, M2) for dt in asymmetric_link_DTs(N))
+    return {test_DT(dt, M2) for dt in asymmetric_link_DTs(N)}
diff --git a/dev/dt_tests.py b/dev/dt_tests.py
index 197aeff..d7c7bf2 100644
--- a/dev/dt_tests.py
+++ b/dev/dt_tests.py
@@ -36,7 +36,7 @@ def test1():
 def test2():
     keys = G.incidence_dict.keys()
     v = keys[0]
-    D = dict( (k, (i, range(10*i, 10*(i+10)))) for i, k in enumerate(keys))
+    D = { k: (i, range(10*i, 10*(i+10))) for i, k in enumerate(keys)}
     for i in range(155000):
         D[v]
 
@@ -44,7 +44,7 @@ def test2():
 def test3():
     keys = G.incidence_dict.keys()
     v = keys[0]
-    D = dict((k, None) for i, k in enumerate(keys))
+    D = {k: None for i, k in enumerate(keys)}
     for i in range(155000):
         D[v]
 
@@ -58,19 +58,19 @@ def test4():
     return v
 
 
-class TestObject():
+class TestObject:
     pass
 
 
 def test5():
-    D = dict([(TestObject(), i) for i in range(10)])
+    D = {TestObject(): i for i in range(10)}
     k = D.keys()[0]
     for i in range(10000000):
         D[k]
 
 
 def test6():
-    D = dict([(i, TestObject()) for i in range(10)])
+    D = {i: TestObject() for i in range(10)}
     k = D.keys()[0]
     for i in range(10000000):
         D[k]
diff --git a/dev/old/fastalex/exhaust.py b/dev/old/fastalex/exhaust.py
index edf6027..b38b6a4 100644
--- a/dev/old/fastalex/exhaust.py
+++ b/dev/old/fastalex/exhaust.py
@@ -38,7 +38,7 @@ def entry_pts_ab(crossing):
     return [CrossingEntryPoint(crossing, v) for v in verts]
 
 
-class StrandIndices():
+class StrandIndices:
     """
     A map from the crossings strands of a link L onto range(n).
     """
@@ -111,7 +111,7 @@ def eval_merges(merges):
         assert eval_merges(m1) == eval_merges(m2)
 
 
-class DrorDatum():
+class DrorDatum:
     """
     The (omega, A) pair which is the invariant defined in the first column of
     http://www.math.toronto.edu/drorbn/Talks/Aarhus-1507/
@@ -192,7 +192,7 @@ def num_overlap(crossing, frontier):
     return len(neighbor_strands.intersection(frontier))
 
 
-class Exhaustion():
+class Exhaustion:
     """
     An exhaustion of a link where crossings are added in one-by-one
     so that the resulting tangle is connected at every stage.
diff --git a/dev/old/seifert_patch.py b/dev/old/seifert_patch.py
index 46dd840..1330c69 100644
--- a/dev/old/seifert_patch.py
+++ b/dev/old/seifert_patch.py
@@ -55,7 +55,7 @@ def seifert_tree(link):
     circles.
     """
     circles = seifert_circles(link)
-    edges = [[set([n]),set([n])] for n in range(len(circles))]
+    edges = [[{n},{n}] for n in range(len(circles))]
     for c in link.crossings:
         under, over = c.entry_points()
         under_circle, over_circle = -1,-1
@@ -92,10 +92,10 @@ def remove_admissible_move(link):
     found_move = False
     for e1, e2 in combinations(tree,2):
         if e1[0] == e2[0]: #edges start at same point
-            circles = set([tree.index(e1), tree.index(e2)])
+            circles = {tree.index(e1), tree.index(e2)}
             found_move = True
         elif e1[1] == e2[1]: #edges end at same point
-            circles = set([tree.index(e1), tree.index(e2)])
+            circles = {tree.index(e1), tree.index(e2)}
             found_move = True
         if found_move:
             move_possible = False
diff --git a/dev/orthogonal/bridge.py b/dev/orthogonal/bridge.py
index 3220e88..ef8f455 100644
--- a/dev/orthogonal/bridge.py
+++ b/dev/orthogonal/bridge.py
@@ -125,7 +125,7 @@ def __new__(self, crossing_strand, link):
         return ans
 
 
-class UpwardLinkDiagram():
+class UpwardLinkDiagram:
     def __init__(self, link):
         self.link = link = link.copy()
         bridge, values = bridge_LP(link)
@@ -185,7 +185,7 @@ def strands_below(self, crossing):
         a = CrossingStrand(crossing, 0)
         b = a.rotate()
         while True:
-            if set([kinds[a], kinds[b]]).issubset(set(['up', 'min'])):
+            if {kinds[a], kinds[b]}.issubset({'up', 'min'}):
                 return a, b
             a, b = b, b.rotate()
 
@@ -284,19 +284,19 @@ def bottom_pairing(snake):
             cs = snake[0]
             return tuple(sorted([to_index(cs), to_index(cs.opposite())]))
 
-        bottom = set(bottom_pairing(snake) for snake in self.snakes)
+        bottom = {bottom_pairing(snake) for snake in self.snakes}
 
         def top_pairing(snake):
             cs = snake[-1]
             cn = self.adjacent_upwards(snake.final)
             return tuple(sorted([to_index(cs), to_index(cn)]))
 
-        top = set(top_pairing(snake) for snake in self.snakes)
+        top = {top_pairing(snake) for snake in self.snakes}
 
         return BridgeDiagram(bottom, [cd[1] for cd in cross_data], top)
 
 
-class BridgeDiagram():
+class BridgeDiagram:
     def __init__(self, bottom, crossings, top):
         self.bottom, self.crossings, self.top = bottom, crossings, top
         self.width = 2 * len(bottom)
diff --git a/dev/orthogonal/ogdf/ortho.py b/dev/orthogonal/ogdf/ortho.py
index 215bab0..fd3b906 100644
--- a/dev/orthogonal/ogdf/ortho.py
+++ b/dev/orthogonal/ogdf/ortho.py
@@ -17,7 +17,7 @@ def link_to_gml_file(L, filename='graphs/link.gml'):
     edges = collections.Counter(tuple(sorted([verts_to_int[e.tail],
                                               verts_to_int[e.head]]))
                                 for e in L.edges)
-    assert set(edges.values()).issubset(set([1, 2]))
+    assert set(edges.values()).issubset({1, 2})
     for (a, b), m in edges.items():
         if m == 2:
             c = len(verts)
diff --git a/dev/orthogonal/orthogonal.py b/dev/orthogonal/orthogonal.py
index bbe59bb..202b9c8 100644
--- a/dev/orthogonal/orthogonal.py
+++ b/dev/orthogonal/orthogonal.py
@@ -324,7 +324,7 @@ def DAG_from_direction(self, kind):
     def chain_coordinates(self, kind):
         D = self.DAG_from_direction(kind)
         chain_coors = topological_numbering(D)
-        return dict( (v,chain_coors[D.vertex_to_chain[v]]) for v in self.vertices )
+        return { v: chain_coors[D.vertex_to_chain[v]] for v in self.vertices }
 
     def basic_grid_embedding(self, rotate=False):
         """
@@ -332,7 +332,7 @@ def basic_grid_embedding(self, rotate=False):
         """
         V = self.chain_coordinates('horizontal')
         H = self.chain_coordinates('vertical')
-        return dict( (v,(H[v], V[v])) for v in self.vertices)
+        return { v: (H[v], V[v]) for v in self.vertices}
 
     def show(self, unit=10, labels=True):
         pos = self.basic_grid_embedding()
@@ -457,8 +457,8 @@ def __init__(self, link):
         self.bend()
         self.orient_edges()
         self.edges = sum([F for F in self], [])
-        strands = set(e.crossing for e in self.edges
-                      if isinstance(e.crossing, Strand))
+        strands = {e.crossing for e in self.edges
+                      if isinstance(e.crossing, Strand)}
         self.strand_CEPs = [CrossingEntryPoint(s, 0) for s in strands]
         for i, c in enumerate(link.crossings):
             c.label = i
@@ -504,7 +504,7 @@ def bend(self):
         flow = networkx.min_cost_flow(N)
         for a, flows in flow.iteritems():
             for b, w_a in flows.iteritems():
-                if w_a and set(['s', 't']).isdisjoint(set([a, b])):
+                if w_a and {'s', 't'}.isdisjoint({a, b}):
                     w_b = flow[b][a]
                     A, B = self[a], self[b]
                     e_a, e_b = A.edge_of_intersection(B)
@@ -596,7 +596,7 @@ def plink_data(self, spacing=None, canvas_width=None):
                 b, a = emb[v.crossing]
             vertex_positions.append( (spacing*(a+1), spacing*(b+1)) )
 
-        vert_indices = dict( (v,i) for i, v in enumerate(self.strand_CEPs))
+        vert_indices = { v: i for i, v in enumerate(self.strand_CEPs)}
         arrows, crossings = self.break_into_arrows()
         arrows = [ (vert_indices[a[0]], vert_indices[a[-1]]) for a in arrows]
 
@@ -668,7 +668,7 @@ def random_link():
 def check_faces(link):
     faces = link.faces()
     assert len(link.vertices) - len(link.edges) + len(faces) == 2
-    assert set(Counter(sum( faces, [] )).values()) == set([1])
+    assert set(Counter(sum( faces, [] )).values()) == {1}
     assert link.is_planar()
 
 
diff --git a/dev/tangle_patch.py b/dev/tangle_patch.py
index 64741b4..b635f48 100644
--- a/dev/tangle_patch.py
+++ b/dev/tangle_patch.py
@@ -327,7 +327,7 @@ def tangle_neighborhood(link,crossing,radius,return_gluings=True,hull=False):
     if hull:
         comps = list(boundary_components(link,crossing,radius))
         largest_comp = max(comps)
-        sides = dict([(cslabel(cross_strand), cross_strand) for cross_strand in adjacent])
+        sides = {cslabel(cross_strand): cross_strand for cross_strand in adjacent}
         c = largest_comp.pop()
         cs = choice(c.crossing_strands())
         exit_strand = meander(cs,sides)[1]
@@ -547,9 +547,9 @@ def fill_in_crossings(link, sides):
     Returns a dictionary with the side (0 or 1) of each crossing.
     """
 
-    crossing_sides = dict([(x[0], sides[x]) for x in sides])
+    crossing_sides = {x[0]: sides[x] for x in sides}
     crossing_labels = map(lambda c: c.label,link.crossings)
-    crossings_to_sort = set(crossing_labels)-set(x[0] for x in sides)
+    crossings_to_sort = set(crossing_labels)-{x[0] for x in sides}
     while crossings_to_sort:
         start_crossing = crossings_to_sort.pop()
         accumulated_crossings = [start_crossing]
diff --git a/spherogram_src/codecs/DT.py b/spherogram_src/codecs/DT.py
index 77d1d78..1d641c0 100644
--- a/spherogram_src/codecs/DT.py
+++ b/spherogram_src/codecs/DT.py
@@ -117,7 +117,7 @@ def upper_pair(self):
         return (0, 2) if bool(first % 2) ^ even_over else (1, 3)
 
 
-class DTPath():
+class DTPath:
     """
     An iterator which starts at a FatEdge and walks around the
     link component containing that edge.  A DTPath raises
@@ -278,7 +278,7 @@ def marked_arc(self, vertex):
         left_path, right_path, vertices = [], [], set()
         vertices.add(vertex)
         try:
-            left, right = [e for e in self(vertex) if e.marked]
+            left, right = (e for e in self(vertex) if e.marked)
         except ValueError:
             raise RuntimeError('Vertex must have two marked edges.')
         for edge, path in (left, left_path), (right, right_path):
@@ -533,7 +533,7 @@ def KLP_dict(self, vertex, indices):
 # meets the next one (so in particular the diagram is connected.
 
 
-class DTcodec():
+class DTcodec:
     """
     Codec for DT codes of a link projection.
     """
diff --git a/spherogram_src/graphs.py b/spherogram_src/graphs.py
index 6073cb0..61ef05c 100644
--- a/spherogram_src/graphs.py
+++ b/spherogram_src/graphs.py
@@ -211,7 +211,7 @@ def set_slot(self, vertex, n):
             raise ValueError('Vertex is not an end of this edge.')
 
 
-class Graph():
+class Graph:
     """
     A set of vertices and a set of edges joining pairs of vertices.
     Vertices are arbitrary hashable objects and should not be
@@ -255,7 +255,7 @@ def incident(self, vertex):
         """
         Return the set of non-loops incident to the vertex.
         """
-        return set(e for e in self.incidence_dict[vertex] if not e.is_loop())
+        return {e for e in self.incidence_dict[vertex] if not e.is_loop()}
 
     def edges_between(self, vertex1, vertex2):
         return self.incident(vertex1).intersection(self.incident(vertex2))
@@ -267,7 +267,7 @@ def children(self, vertex):
         """
         Return the set of distinct adjacent vertices.
         """
-        return set(e(vertex) for e in self.incidence_dict[vertex])
+        return {e(vertex) for e in self.incidence_dict[vertex]}
 
     def add_edge(self, *args, **kwargs):
         edge = self.Edge(*args, **kwargs)
@@ -440,7 +440,7 @@ def one_min_cut(self, source, sink, capacity=None):
             for e in self.edges:
                 if e not in residual:
                     residual[e] = float('inf')
-        full_edges = set(e for e in self.edges if residual[e] == 0)
+        full_edges = {e for e in self.edges if residual[e] == 0}
         children = {}
         for vertex in self.vertices:
             children[vertex] = set()
@@ -448,7 +448,7 @@ def one_min_cut(self, source, sink, capacity=None):
         path_list = []
         while True:
             # Try to find a new path from source to sink
-            parents, cut_set, reached_sink = {}, set([source]), False
+            parents, cut_set, reached_sink = {}, {source}, False
             generator = self.breadth_first_edges(
                 source=source,
                 forbidden=full_edges,
@@ -483,9 +483,9 @@ def one_min_cut(self, source, sink, capacity=None):
         # Find the cut edges.
         cut_edges = set()
         for vertex in cut_set:
-            cut_edges |= set(edge for edge in self.edges
+            cut_edges |= {edge for edge in self.edges
                              if vertex in edge
-                             and edge(vertex) not in cut_set)
+                             and edge(vertex) not in cut_set}
         # Find the unsaturated edges.
         unsaturated = [e for e in self.edges if residual[e] > 0]
         flow_dict = dict.fromkeys(self.edges, 0)
@@ -525,7 +525,7 @@ def merge(self, V1, V2):
         new_vertex = V1 | V2
         if new_vertex in self.vertices:
             raise ValueError('Merged vertex already exists!')
-        self.edges -= set(e for e in self.edges if V1 in e and V2 in e)
+        self.edges -= {e for e in self.edges if V1 in e and V2 in e}
         self.vertices.remove(V1)
         self.vertices.remove(V2)
         old_vertices = (V1, V2)
@@ -775,8 +775,8 @@ def outgoing(self, vertex):
         """
         Return the set of non-loop edges which *begin* at the vertex.
         """
-        return set(e for e in self(vertex)
-                   if e.tail is vertex and e.head is not vertex)
+        return {e for e in self(vertex)
+                   if e.tail is vertex and e.head is not vertex}
 
     # Force flows to go in the direction of the edge.
     flow_incident = outgoing
@@ -785,15 +785,15 @@ def incoming(self, vertex):
         """
         Return the set of non-loop edges which *end* at the vertex.
         """
-        return set(e for e in self(vertex)
-                   if e.head is vertex and e.tail is not vertex)
+        return {e for e in self(vertex)
+                   if e.head is vertex and e.tail is not vertex}
 
     def children(self, vertex):
         """
         Return the set of distinct vertices which are endpoints of
         outgoing non-loop edges.
         """
-        return set(e(vertex) for e in self.outgoing(vertex))
+        return {e(vertex) for e in self.outgoing(vertex)}
 
     def indegree(self, vertex):
         return len([e for e in self.incidence_dict[vertex] if e.head is vertex])
@@ -868,7 +868,7 @@ def component_DAG(self):
         return StrongConnector(self).DAG()
 
 
-class StrongConnector():
+class StrongConnector:
     """
     Finds strong components of a digraph using Tarjan's algorithm;
     see http://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
@@ -984,7 +984,7 @@ def incomparable(self, x):
         >>> sorted(P.incomparable(3))
         [1, 2]
         """
-        return self.elements - self.smaller[x] - self.larger[x] - set([x])
+        return self.elements - self.smaller[x] - self.larger[x] - {x}
 
     def smallest(self):
         """
@@ -1043,7 +1043,7 @@ def XXclosed_subsets(self, start=None):
             self.closed.add(start)
             yield start
         for element in complement:
-            extended = self.closure(start | set([element]))
+            extended = self.closure(start | {element})
             yield from self.XXclosed_subsets(extended)
 
     def XXXclosed_subsets(self, start=None):
@@ -1069,7 +1069,7 @@ def XXXclosed_subsets(self, start=None):
         for element in start:
             children.update(self.successors[element] - start)
         for child in children:
-            extended = self.closure(start | set([child]))
+            extended = self.closure(start | {child})
             yield from self.XXXclosed_subsets(extended)
 
     def closed_subsets(self):
@@ -1117,7 +1117,7 @@ def powerset(S):
         for x in X:
             break
         X.remove(x)
-        singleton = set([x])
+        singleton = {x}
         for Y in powerset(X):
             yield (singleton | Y)
         yield X
diff --git a/spherogram_src/links/alexander.py b/spherogram_src/links/alexander.py
index cc03e09..5d55e3e 100644
--- a/spherogram_src/links/alexander.py
+++ b/spherogram_src/links/alexander.py
@@ -46,7 +46,7 @@ def entry_pts_ab(crossing):
     return [CrossingEntryPoint(crossing, v) for v in verts]
 
 
-class StrandIndices():
+class StrandIndices:
     """
     A map from the crossings strands of a link L onto range(n).
     """
@@ -118,7 +118,7 @@ def eval_merges(merges):
         assert eval_merges(m1) == eval_merges(m2)
 
 
-class DrorDatum():
+class DrorDatum:
     """
     The (omega, A) pair which is the invariant defined in the first column of
     http://www.math.toronto.edu/drorbn/Talks/Aarhus-1507/
@@ -151,11 +151,11 @@ def merge(self, cs_a, cs_b):
 
 
 def num_overlap(crossing, frontier):
-    neighbor_strands = set(cs.opposite() for cs in crossing.crossing_strands())
+    neighbor_strands = {cs.opposite() for cs in crossing.crossing_strands()}
     return len(neighbor_strands.intersection(frontier))
 
 
-class Exhaustion():
+class Exhaustion:
     """
     An exhaustion of a link where crossings are added in one-by-one
     so that the resulting tangle is connected at every stage.
diff --git a/spherogram_src/links/exhaust.py b/spherogram_src/links/exhaust.py
index 1630c40..84b604d 100644
--- a/spherogram_src/links/exhaust.py
+++ b/spherogram_src/links/exhaust.py
@@ -6,7 +6,7 @@
 def insert_space(point_dict, i):
     """
     Insert two new points which will be labeled i and i + 1.
-        """
+    """
     ans = {}
     for a, v in point_dict.items():
         if a >= i:
@@ -28,7 +28,7 @@ def remove_space(point_dict, i):
     return ans
 
 
-class Event():
+class Event:
     """
     There are three kinds of events:
 
@@ -59,7 +59,7 @@ def __repr__(self):
         return repr(ans)
 
 
-class MorseEncoding():
+class MorseEncoding:
     """
     A MorseEncoding is a concrete encoding of a Morse diagram of an
     oriented link in the sprit of:
@@ -146,7 +146,7 @@ def __iter__(self):
         return self.events.__iter__()
 
 
-class BiDict():
+class BiDict:
     """
     A bijective mapping from range(n) to a set of hashable non-integers.
 
@@ -291,7 +291,7 @@ def biggest_all_consecutive_overlap(self):
         return random.choice(good_choices)
 
 
-class MorseExhaustion():
+class MorseExhaustion:
     """
     An exhaustion of a link where crossings are added in one-by-one
     so that the resulting tangle is connected at every stage.
diff --git a/spherogram_src/links/extra_tests.py b/spherogram_src/links/extra_tests.py
index e3d0f0f..b82e026 100644
--- a/spherogram_src/links/extra_tests.py
+++ b/spherogram_src/links/extra_tests.py
@@ -7,7 +7,7 @@
 
 
 def figure8():
-    a, b, c, d = [Crossing(x) for x in 'abcd']
+    a, b, c, d = (Crossing(x) for x in 'abcd')
     a[0] = c[1]
     a[1] = d[0]
     a[2] = b[1]
@@ -27,7 +27,7 @@ def punct_torus():
 
 
 def whitehead():
-    a, b, c, d, e = crossings = [Crossing(x) for x in 'abcde']
+    a, b, c, d, e = crossings = (Crossing(x) for x in 'abcde')
     a[0] = b[3]
     a[1] = d[0]
     a[2] = d[3]
@@ -56,7 +56,7 @@ def knot(fractions):
     if len(fractions) == 1:
         return RationalTangle(*fractions[0]).denominator_closure()
     else:
-        A, B, C = [RationalTangle(*f) for f in fractions]
+        A, B, C = (RationalTangle(*f) for f in fractions)
         T = A + B + C
         return T.numerator_closure()
 
diff --git a/spherogram_src/links/invariants.py b/spherogram_src/links/invariants.py
index 96e5858..a0e1909 100644
--- a/spherogram_src/links/invariants.py
+++ b/spherogram_src/links/invariants.py
@@ -425,7 +425,7 @@ def black_graph(self):
                 b = set(faces[j])
                 s = a.union(b)
                 for x in range(len(self.crossings)):
-                    total = set(self.crossings[x][i] for i in range(4))
+                    total = {self.crossings[x][i] for i in range(4)}
                     if total.issubset(s):
                         coords.append((tuple(faces[i]), tuple(faces[j]),
                                        self.crossings[x]))  # label by the crossing.
diff --git a/spherogram_src/links/jones.py b/spherogram_src/links/jones.py
index f0d333b..9ebb272 100644
--- a/spherogram_src/links/jones.py
+++ b/spherogram_src/links/jones.py
@@ -86,7 +86,7 @@ def follow(a):
     return PerfectMatching(new_match), circle
 
 
-class VElement():
+class VElement:
     """
     An element of some V_{0, n} which is the free R-module on P_{0, n}
 
diff --git a/spherogram_src/links/jones_old.py b/spherogram_src/links/jones_old.py
index 75eaebd..7f1de4b 100644
--- a/spherogram_src/links/jones_old.py
+++ b/spherogram_src/links/jones_old.py
@@ -107,7 +107,7 @@ def is_externally_active(G, T, e):
 def _edge_sign(K, edge):
     "Returns the sign (+/- 1) associated to given edge in the black graph."
     crossing = edge[2]
-    if set(((crossing, 0), (crossing, 1))).issubset(set(edge[0])) or set(((crossing, 0), (crossing, 1))).issubset(set(edge[1])):
+    if {(crossing, 0), (crossing, 1)}.issubset(set(edge[0])) or {(crossing, 0), (crossing, 1)}.issubset(set(edge[1])):
         return +1
     return -1
 
diff --git a/spherogram_src/links/links_base.py b/spherogram_src/links/links_base.py
index faf3751..3469d5b 100644
--- a/spherogram_src/links/links_base.py
+++ b/spherogram_src/links/links_base.py
@@ -68,7 +68,7 @@ def lookup_DT_code_by_name(name):
             continue
 
 
-class Crossing():
+class Crossing:
     """
     See "doc.pdf" for the conventions.  The sign of a crossing can be in {0,
     +1, -1}.  In the first case, the strands at the crossings can have
@@ -130,8 +130,8 @@ def rotate(v):
             else:
                 self.adjacent[i] = (self, (j - s) % 4)
 
-        self.directions = set((rotate(a), rotate(b))
-                              for a, b in self.directions)
+        self.directions = {(rotate(a), rotate(b))
+                              for a, b in self.directions}
 
     def rotate_by_90(self):
         "Effectively switches the crossing"
@@ -320,7 +320,7 @@ def add(self, x):
         self[x] = len(self)
 
 
-class Strand():
+class Strand:
     """
     When constructing links, it's convenient to have strands as well
     as crossings.  These are stripped by the Link class when it
@@ -371,7 +371,7 @@ def enumerate_lists(lists, n=0, filter=lambda x: True):
     return ans
 
 
-class Link():
+class Link:
     """
     Links are made from Crossings.  The general model is that of the PD
     diagrams used in `KnotTheory <http://katlas.org/wiki/Planar_Diagrams>`_.
@@ -591,7 +591,7 @@ def _crossings_from_PD_code(self, code):
                 else:
                     gluings[x] = [(c, i)]
 
-        if set(len(v) for v in gluings.values()) != set([2]):
+        if {len(v) for v in gluings.values()} != {2}:
             raise ValueError("PD code isn't consistent")
 
         component_starts = self._component_starts_from_PD(
@@ -629,7 +629,7 @@ def _component_starts_from_PD(self, code, labels, gluings):
             if c1 == c2:
                 # loop at strand, take next strand to be next smallest label
                 # on crossing
-                next_label = min(set(code[c1]) - set([m]))
+                next_label = min(set(code[c1]) - {m})
                 direction = (c1, code[c1].index(next_label))
                 starts.append(direction)
             else:
@@ -1527,7 +1527,7 @@ def vertex_to_KLP(c, v):
     return ['Ybackward', 'Xforward', 'Yforward', 'Xbackward'][i]
 
 
-class KLPCrossing():
+class KLPCrossing:
     """
     SnapPea uses a convention where the orientation
     of the strands is fixed in the master picture but
diff --git a/spherogram_src/links/morse.py b/spherogram_src/links/morse.py
index b41b865..4a91864 100644
--- a/spherogram_src/links/morse.py
+++ b/spherogram_src/links/morse.py
@@ -151,7 +151,7 @@ def __new__(self, crossing_strand, link):
         return ans
 
 
-class MorseLinkDiagram():
+class MorseLinkDiagram:
     """
     A planar link diagram with a height function on R^2 which
     is Morse on the link.
@@ -228,7 +228,7 @@ def strands_below(self, crossing):
         kinds = self.orientations
         a = CrossingStrand(crossing, 0)
         b = a.rotate()
-        upmin = set(['up', 'min'])
+        upmin = {'up', 'min'}
         test_a = kinds[a] in upmin
         while True:
             test_b = kinds[b] in upmin
@@ -364,19 +364,19 @@ def bottom_pairing(snake):
             cs = snake[0]
             return tuple(sorted([to_index(cs), to_index(cs.opposite())]))
 
-        bottom = set(bottom_pairing(snake) for snake in self.snakes)
+        bottom = {bottom_pairing(snake) for snake in self.snakes}
 
         def top_pairing(snake):
             cs = snake[-1]
             cn = self.adjacent_upwards(snake.final)
             return tuple(sorted([to_index(cs), to_index(cn)]))
 
-        top = set(top_pairing(snake) for snake in self.snakes)
+        top = {top_pairing(snake) for snake in self.snakes}
 
         return BridgeDiagram(bottom, [cd[1] for cd in cross_data], top)
 
 
-class BridgeDiagram():
+class BridgeDiagram:
     """
     A proper bridge diagram of a link, that is, a height function
     where all the mins are below all the maxes.
diff --git a/spherogram_src/links/ordered_set.py b/spherogram_src/links/ordered_set.py
index de622bf..dd31425 100644
--- a/spherogram_src/links/ordered_set.py
+++ b/spherogram_src/links/ordered_set.py
@@ -1,4 +1,4 @@
-class OrderedSet():
+class OrderedSet:
     def __init__(self, iterable=None):
         if iterable is not None:
             self.elts = {e: None for e in iterable}
diff --git a/spherogram_src/links/orthogonal.py b/spherogram_src/links/orthogonal.py
index 7590c98..fa9cb74 100644
--- a/spherogram_src/links/orthogonal.py
+++ b/spherogram_src/links/orthogonal.py
@@ -53,7 +53,7 @@ def basic_topological_numbering(G):
     """
     Finds an optimal weighted topological numbering a directed acyclic graph
     """
-    in_valences = dict((v, G.indegree(v)) for v in G.vertices)
+    in_valences = {v: G.indegree(v) for v in G.vertices}
     numbering = {}
     curr_sources = [v for v, i in in_valences.items() if i == 0]
     curr_number = 0
@@ -325,7 +325,7 @@ def DAG_from_direction(self, kind):
     def chain_coordinates(self, kind):
         D = self.DAG_from_direction(kind)
         chain_coors = topological_numbering(D)
-        return dict((v, chain_coors[D.vertex_to_chain[v]]) for v in self.vertices)
+        return {v: chain_coors[D.vertex_to_chain[v]] for v in self.vertices}
 
     def basic_grid_embedding(self, rotate=False):
         """
@@ -333,7 +333,7 @@ def basic_grid_embedding(self, rotate=False):
         """
         V = self.chain_coordinates('horizontal')
         H = self.chain_coordinates('vertical')
-        return dict((v, (H[v], V[v])) for v in self.vertices)
+        return {v: (H[v], V[v]) for v in self.vertices}
 
     def show(self, unit=10, labels=True):
         from sage.all import circle, text, line, Graphics
@@ -362,7 +362,7 @@ def show(self, unit=10, labels=True):
 class Face(CyclicList):
     def __init__(self, link, crossing_strands, exterior=False):
         list.__init__(self, crossing_strands)
-        self.edges = dict((c.oriented(), c) for c in crossing_strands)
+        self.edges = {c.oriented(): c for c in crossing_strands}
         self.exterior = exterior
         self.turns = [1 for e in self]
 
@@ -502,7 +502,7 @@ def bend(self):
         flow = networkx.min_cost_flow(N)
         for a, flows in flow.items():
             for b, w_a in flows.items():
-                if w_a and set(['s', 't']).isdisjoint(set([a, b])):
+                if w_a and {'s', 't'}.isdisjoint({a, b}):
                     w_b = flow[b][a]
                     A, B = self[a], self[b]
                     e_a, e_b = A.edge_of_intersection(B)
@@ -607,7 +607,7 @@ def plink_data(self):
                 b, a = emb[v.crossing]
             vertex_positions.append((10 * (a + 1), 10 * (b + 1)))
 
-        vert_indices = dict((v, i) for i, v in enumerate(self.strand_CEPs))
+        vert_indices = {v: i for i, v in enumerate(self.strand_CEPs)}
         arrows, crossings = self.break_into_arrows()
         arrows = [(vert_indices[a[0]], vert_indices[a[-1]]) for a in arrows]
 
diff --git a/spherogram_src/links/planar_isotopy.py b/spherogram_src/links/planar_isotopy.py
index ee1356b..8a9d8c0 100644
--- a/spherogram_src/links/planar_isotopy.py
+++ b/spherogram_src/links/planar_isotopy.py
@@ -188,7 +188,7 @@ def all_cross_strands(tangle):
                 other_ends_seen.append(end)
     orientations, over_or_under = crossing_orientations(strands)
     cs_seen = [cs for strand in strands for cs in strand]
-    seen_once = set(cs[0] for cs in cs_seen)
+    seen_once = {cs[0] for cs in cs_seen}
     for crossing in orientations:
         seen_once.remove(crossing)
     for strand in strands:
diff --git a/spherogram_src/links/seifert.py b/spherogram_src/links/seifert.py
index 44ec1fe..366d2be 100644
--- a/spherogram_src/links/seifert.py
+++ b/spherogram_src/links/seifert.py
@@ -79,7 +79,7 @@ def seifert_tree(link):
     True
     """
     circles = seifert_circles(link)
-    edges = [[set([n]), set([n])] for n in range(len(circles))]
+    edges = [[{n}, {n}] for n in range(len(circles))]
     for c in link.crossings:
         under, over = c.entry_points()
         under_circle, over_circle = -1, -1
@@ -116,10 +116,10 @@ def remove_admissible_move(link):
     found_move = False
     for e1, e2 in combinations(tree, 2):
         if e1[0] == e2[0]:  # edges start at same point
-            circles = set([tree.index(e1), tree.index(e2)])
+            circles = {tree.index(e1), tree.index(e2)}
             found_move = True
         elif e1[1] == e2[1]:  # edges end at same point
-            circles = set([tree.index(e1), tree.index(e2)])
+            circles = {tree.index(e1), tree.index(e2)}
             found_move = True
         if found_move:
             move_possible = False
@@ -301,7 +301,7 @@ def seifert_matrix(link, return_matrix_of_types=False):
     from a braid representation." (2007).
     """
     arrows = braid_arrows(link)
-    strands = set(x[1] for x in arrows)
+    strands = {x[1] for x in arrows}
     grouped_by_strand = [[x for x in arrows if x[1] == strand]
                          for strand in strands]
     hom_gens = [[(group[i][0], group[i + 1][0], group[i][2], group[i + 1][2])
diff --git a/spherogram_src/links/simplify.py b/spherogram_src/links/simplify.py
index e544781..393bd6b 100644
--- a/spherogram_src/links/simplify.py
+++ b/spherogram_src/links/simplify.py
@@ -52,10 +52,10 @@ def reidemeister_I(link, C):
     for i in range(4):
         if C.adjacent[i] == (C, (i + 1) % 4):
             (A, a), (B, b) = C.adjacent[i + 2], C.adjacent[i + 3]
-            elim = set([C])
+            elim = {C}
             if C != A:
                 A[a] = B[b]
-                changed = set([A, B])
+                changed = {A, B}
 
     remove_crossings(link, elim)
     return elim, changed
@@ -81,13 +81,13 @@ def reidemeister_I_and_II(link, A):
                     X, x = A.adjacent[a + 3]
                     Y, y = B.adjacent[b + 1]
                     Z, z = B.adjacent[b + 2]
-                    eliminated = set([A, B])
+                    eliminated = {A, B}
                     if W != B:
                         W[w] = Z[z]
-                        changed.update(set([W, Z]))
+                        changed.update({W, Z})
                     if X != B:
                         X[x] = Y[y]
-                        changed.update(set([X, Y]))
+                        changed.update({X, Y})
                     remove_crossings(link, eliminated)
                     break
 
@@ -147,7 +147,7 @@ def possible_type_III_moves(link):
             if sum(ce.strand_index % 2 for ce in face) in [1, 2]:
                 while(face[1][1] % 2 != 0 or face[2][1] % 2 != 1):    # renumber face_list
                     face = [face[1], face[2], face[0]]
-                if len(set(e.crossing for e in face)) == 3:  # No repeated crossings
+                if len({e.crossing for e in face}) == 3:  # No repeated crossings
                     ans.append(face)
     return ans
 
@@ -164,8 +164,8 @@ def reidemeister_III(link, triple):
     Performs the given type III move.  Modifies the given link but doesn't
     update its lists of link components.
     """
-    A, B, C = [t.crossing for t in triple]
-    a, b, c = [t.strand_index for t in triple]
+    A, B, C = (t.crossing for t in triple)
+    a, b, c = (t.strand_index for t in triple)
     # We insert Strands around the border of the triple to make the code more
     # transparent and eliminate some special cases.
     old_border = [(C, c - 1), (C, c - 2), (A, a - 1),
@@ -388,7 +388,7 @@ def pickup_strand(link, dual_graph, kind, strand):
         # of the rest of the components.
         remove_strand(link, [startcep] + strand)
         return len(strand)
-    crossing_set = set(cep.crossing for cep in strand)
+    crossing_set = {cep.crossing for cep in strand}
     endpoint = strand[-1].next()
 
     if endpoint.crossing in crossing_set:
diff --git a/spherogram_src/links/tangles.py b/spherogram_src/links/tangles.py
index 6d327fd..5dc201d 100644
--- a/spherogram_src/links/tangles.py
+++ b/spherogram_src/links/tangles.py
@@ -77,7 +77,7 @@ def decode_boundary(boundary):
     return (m, n)
 
 
-class Tangle():
+class Tangle:
     def __init__(self, boundary=2, crossings=None, entry_points=None, label=None):
         """
         A tangle is a fragment of a Link with some number of boundary
diff --git a/spherogram_src/links/test/old_testing_code.py b/spherogram_src/links/test/old_testing_code.py
index e3d0f0f..b82e026 100644
--- a/spherogram_src/links/test/old_testing_code.py
+++ b/spherogram_src/links/test/old_testing_code.py
@@ -7,7 +7,7 @@
 
 
 def figure8():
-    a, b, c, d = [Crossing(x) for x in 'abcd']
+    a, b, c, d = (Crossing(x) for x in 'abcd')
     a[0] = c[1]
     a[1] = d[0]
     a[2] = b[1]
@@ -27,7 +27,7 @@ def punct_torus():
 
 
 def whitehead():
-    a, b, c, d, e = crossings = [Crossing(x) for x in 'abcde']
+    a, b, c, d, e = crossings = (Crossing(x) for x in 'abcde')
     a[0] = b[3]
     a[1] = d[0]
     a[2] = d[3]
@@ -56,7 +56,7 @@ def knot(fractions):
     if len(fractions) == 1:
         return RationalTangle(*fractions[0]).denominator_closure()
     else:
-        A, B, C = [RationalTangle(*f) for f in fractions]
+        A, B, C = (RationalTangle(*f) for f in fractions)
         T = A + B + C
         return T.numerator_closure()
 
diff --git a/spherogram_src/links/test/test_montesinos.py b/spherogram_src/links/test/test_montesinos.py
index 835cc96..fb35cc4 100644
--- a/spherogram_src/links/test/test_montesinos.py
+++ b/spherogram_src/links/test/test_montesinos.py
@@ -14,7 +14,7 @@ def knot(fractions):
     if len(fractions) == 1:
         return RationalTangle(*fractions[0]).denominator_closure()
     else:
-        A, B, C = [RationalTangle(*f) for f in fractions]
+        A, B, C = (RationalTangle(*f) for f in fractions)
         T = A + B + C
         return T.numerator_closure()
 
diff --git a/spherogram_src/links/twist.py b/spherogram_src/links/twist.py
index 1f7dec2..1504415 100644
--- a/spherogram_src/links/twist.py
+++ b/spherogram_src/links/twist.py
@@ -69,7 +69,7 @@ def __len__(self):
 
 
 def is_end_of_twist_region(crossing) -> bool:
-    return len(set(C for (C, i) in crossing.adjacent)) == 3
+    return len({C for (C, i) in crossing.adjacent}) == 3
 
 
 def make_twist_regions_consistent(link):
diff --git a/spherogram_src/presentations.py b/spherogram_src/presentations.py
index 4023106..6136500 100644
--- a/spherogram_src/presentations.py
+++ b/spherogram_src/presentations.py
@@ -3,7 +3,7 @@
 import operator
 
 
-class Alphabet():
+class Alphabet:
     """
     An Alphabet translates between integers and strings.
     Call as a function to go from string to integer; use getitem
@@ -255,7 +255,7 @@ def __ge__(self, other):
         return not self < other
 
 
-class WhiteheadMove():
+class WhiteheadMove:
     """
     Holds the data describing a Whitehead move.
     """
@@ -283,7 +283,7 @@ def __repr__(self):
         return ', '.join(subs)
 
 
-class Presentation():
+class Presentation:
     """
     A Presentation contains a list of CyclicWords as relators and a
     list of (integer) letters as generators.  The generators are
@@ -451,7 +451,7 @@ def level_orbit(self, verbose=False):
         """
         S = self.signature()
         queue = deque([(None, None, self, S)])
-        seen = set([S])
+        seen = {S}
         while queue:
             parent, move, pres, sig = queue.popleft()
             for a, A in pres.level_transformations():
@@ -495,7 +495,7 @@ def magma_string(self):
         return ans + '>'
 
 
-class CanonizeNode():
+class CanonizeNode:
     def __init__(self, presentation, remaining, ordering=[]):
         self.presentation = presentation
         self.generators = presentation.generators