re-added sigmoid

experiments/tower_defense.jl

@@ -662,7 +662,14 @@ Attacker cost function
 β: vector containing P2's (attacker) preference parameters for each world.
 """
 function J_2(u, v, β)
-    -sum([β[ii]^(v[ii] - u[ii]) for ii in eachindex(β)])
+    # -sum([β[ii]^(v[ii] - u[ii]) for ii in eachindex(β)])
+    δ = [β[ii]*v[ii] - u[ii] for ii in eachindex(β)]
+    -sum([activate(δ[j])*(β[j]*v[j]-u[j])^2 for j in eachindex(β)])
+
+end
+
+function activate(δ; k=10.0)
+    return 1/(1 + exp(-2 * δ * k))
 end
 
 """