diff --git a/src/propeller/session.cljc b/src/propeller/session.cljc
index e638c35..e0469cb 100755
--- a/src/propeller/session.cljc
+++ b/src/propeller/session.cljc
@@ -35,7 +35,7 @@
 #_(genome/plushy->push
     (genome/make-random-plushy (get-stack-instructions #{:float :integer :exec :boolean}) 20))
 
-(gp/gp {:instructions            propeller.problems.software.number-io/instructions
+#_(gp/gp {:instructions            propeller.problems.software.number-io/instructions
         :error-function          propeller.problems.software.number-io/error-function
         :max-generations         500
         :population-size         500
@@ -46,3 +46,30 @@
         :umad-rate               0.1
         :variation               {:umad 0.5 :crossover 0.5}
         :elitism                 false})
+
+#_(gp/gp {:instructions            propeller.problems.simple-regression/instructions
+        :error-function          propeller.problems.simple-regression/error-function
+        :max-generations         500
+        :population-size         500
+        :max-initial-plushy-size 100
+        :step-limit              200
+        :parent-selection        :tournament
+        :tournament-size         5
+        :umad-rate               0.01
+        :variation               {:umad 1.0
+                                  :crossover 0.0}
+        :elitism                 false})
+
+(gp/gp {:instructions            propeller.problems.simple-regression/instructions
+        :error-function          propeller.problems.simple-regression/error-function
+        :max-generations         500
+        :population-size         500
+        :max-initial-plushy-size 100
+        :step-limit              200
+        :parent-selection        :tournament
+        :tournament-size         5
+        :umad-rate               0.1
+        :variation               {:umad 1.0
+                                  :crossover 0.0}
+        :elitism                 false})
+
diff --git a/src/propeller/variation.cljc b/src/propeller/variation.cljc
index ffe0e9e..8b98f18 100755
--- a/src/propeller/variation.cljc
+++ b/src/propeller/variation.cljc
@@ -84,21 +84,21 @@
          [xover add del] (if (:diploid argmap)
                            [diploid-crossover diploid-uniform-addition diploid-uniform-deletion]
                            [crossover uniform-addition uniform-deletion])
-         xover-rate (or (:crossover (:variation argmap)) 0)
-         umad-rate (or (:umad (:variation argmap)) 0)
-         flip-rate (or (:flip (:variation argmap)) 0)]
+         xover-prob (or (:crossover (:variation argmap)) 0)
+         umad-prob (or (:umad (:variation argmap)) 0)
+         flip-prob (or (:flip (:variation argmap)) 0)]
      (cond
-       (< prob xover-rate)
+       (< prob xover-prob)
        (xover (:plushy (selection/select-parent pop argmap))
               (:plushy (selection/select-parent pop argmap)))
        ;
-       (< prob (+ xover-rate umad-rate))
+       (< prob (+ xover-prob umad-prob))
        (del (add (:plushy (selection/select-parent pop argmap))
                  (:instructions argmap)
-                 umad-rate)
-            umad-rate)
+                 (:umad-rate argmap))
+            (:umad-rate argmap))
        ;
-       (< prob (+ xover-rate umad-rate flip-rate))
-       (diploid-flip (:plushy (selection/select-parent pop argmap)) flip-rate)
+       (< prob (+ xover-prob umad-prob flip-prob))
+       (diploid-flip (:plushy (selection/select-parent pop argmap)) flip-prob)
        ;
        :else (:plushy (selection/select-parent pop argmap))))})