diff --git a/docs/∆-Nets: Interaction-Based System for Optimal Parallel λ-Reduction.pdf b/docs/∆-Nets: Interaction-Based System for Optimal Parallel λ-Reduction.pdf
new file mode 100644
index 0000000..11e285a
Binary files /dev/null and b/docs/∆-Nets: Interaction-Based System for Optimal Parallel λ-Reduction.pdf differ
diff --git a/pkg/deltanet/deltanet.go b/pkg/deltanet/deltanet.go
index be3f3ff..bea8298 100644
--- a/pkg/deltanet/deltanet.go
+++ b/pkg/deltanet/deltanet.go
@@ -2,8 +2,5 @@
 package deltanet
 
 type Graph struct {
-	nodes []Node
-}
-
-type Node interface {
+	Nodes []Node
 }
diff --git a/pkg/deltanet/node.go b/pkg/deltanet/node.go
new file mode 100644
index 0000000..91a77d0
--- /dev/null
+++ b/pkg/deltanet/node.go
@@ -0,0 +1,94 @@
+package deltanet
+
+/** ------------------------------------------------------------------------- */
+
+// A connection between exactly two nodes in a graph.
+type Edge struct {
+	A, B Node
+}
+
+// Returns all nodes the edge is connected to.
+func (e Edge) GetConnections() []Node { return []Node{e.A, e.B} }
+
+// Determines if a node is connected via this edge.
+func (e Edge) IsConnected(n Node) bool { return e.A == n || e.B == n }
+
+// Swaps an edges connected with one node, for another.
+func (e *Edge) Swap(from Node, to Node) {
+	if e.A == from {
+		e.A = to
+	}
+	if e.B == from {
+		e.B = to
+	}
+}
+
+// Returns true if the edge is connected to each node via their pricniple ports.
+func (e Edge) IsPrincipleEdge() bool {
+	return e.A.GetMainPort() == e && e.B.GetMainPort() == e
+}
+
+/** ------------------------------------------------------------------------- */
+
+type Node interface {
+	// Returns the principle port that the node is attached to.
+	GetMainPort() Edge
+
+	// Returns all auxiliary ports that the node has. These ports are guaranteed
+	// to be ordered clockwise, as they would appear graphically.
+	GetAuxPorts() []Edge
+
+	// Returns the label of the node. May be blank.
+	GetLabel() string
+}
+
+/** ------------------------------------------------------------------------- */
+
+type EraserNode struct {
+	Main Edge
+}
+
+func (n EraserNode) GetLabel() string    { return "Ⓧ" }
+func (n EraserNode) GetMainPort() Edge   { return n.Main }
+func (n EraserNode) GetAuxPorts() []Edge { return []Edge{} }
+
+/** ------------------------------------------------------------------------- */
+
+type ReplicatorNode struct {
+	Main   Edge
+	Level  uint
+	Aux    []Edge
+	Deltas []int
+}
+
+func (n ReplicatorNode) GetLabel() string    { return "" }
+func (n ReplicatorNode) GetMainPort() Edge   { return n.Main }
+func (n ReplicatorNode) GetAuxPorts() []Edge { return n.Aux }
+
+// Returns the level of the replicator node.
+func (n ReplicatorNode) GetLevel() uint { return n.Level }
+
+/** ------------------------------------------------------------------------- */
+
+type FanNode struct {
+	Label       string
+	Main        Edge
+	Left, Right Edge
+}
+
+func (n FanNode) GetLabel() string    { return n.Label }
+func (n FanNode) GetMainPort() Edge   { return n.Main }
+func (n FanNode) GetAuxPorts() []Edge { return []Edge{n.Left, n.Right} }
+
+/** ------------------------------------------------------------------------- */
+
+type TerminalNode struct {
+	Label string
+	Main  Edge
+}
+
+func (n TerminalNode) GetLabel() string    { return n.Label }
+func (n TerminalNode) GetMainPort() Edge   { return n.Main }
+func (n TerminalNode) GetAuxPorts() []Edge { return []Edge{} }
+
+/** ------------------------------------------------------------------------- */