<NME> Optimizable.java
<BEF> ADDFILE
<MSG> add interface Optimizable

<DFF> @@ -0,0 +1,16 @@
+package edu.neu.ccs.pyramid.optimization;
+
+import org.apache.mahout.math.Vector;
+
+/**
+ * Created by chengli on 12/7/14.
+ * inspired by the design of mallet
+ */
+public interface Optimizable {
+    Vector getParameters();
+
+    public interface ByGradient extends Optimizable {
+        Vector getGradient();
+    }
+
+}

add interface Optimizable