diff --git a/finalseg/prob_emit.go b/finalseg/prob_emit.go
index c5e6f2d..3832a22 100644
--- a/finalseg/prob_emit.go
+++ b/finalseg/prob_emit.go
@@ -1,9 +1,9 @@
 package finalseg
 
-var ProbEmit = make(map[byte]map[rune]float64)
+var probEmit = make(map[byte]map[rune]float64)
 
 func init() {
-	ProbEmit['B'] = map[rune]float64{'\u4e00': -3.6544978750449433,
+	probEmit['B'] = map[rune]float64{'\u4e00': -3.6544978750449433,
 		'\u4e01': -8.125041941842026,
 		'\u4e03': -7.817392401429855,
 		'\u4e07': -6.3096425804013165,
@@ -6860,7 +6860,7 @@ func init() {
 		'\u9f9a': -9.557108305917183,
 		'\u9f9c': -10.895131537474946,
 		'\u9f9f': -10.895131537474946}
-	ProbEmit['E'] = map[rune]float64{'\u4e00': -6.044987536255073,
+	probEmit['E'] = map[rune]float64{'\u4e00': -6.044987536255073,
 		'\u4e01': -9.075800412310807,
 		'\u4e03': -9.198842005220659,
 		'\u4e07': -7.655326112989935,
@@ -14299,7 +14299,7 @@ func init() {
 		'\u9f9b': -12.729311722586953,
 		'\u9f9c': -10.574067217491615,
 		'\u9f9f': -10.574067217491615}
-	ProbEmit['M'] = map[rune]float64{'\u4e00': -4.428158526435913,
+	probEmit['M'] = map[rune]float64{'\u4e00': -4.428158526435913,
 		'\u4e01': -7.932945687598502,
 		'\u4e03': -6.559715525951586,
 		'\u4e07': -6.139922374120667,
@@ -20708,7 +20708,7 @@ func init() {
 		'\u9f9a': -14.14915250738439,
 		'\u9f9c': -11.058110054026073,
 		'\u9f9f': -11.058110054026073}
-	ProbEmit['S'] = map[rune]float64{'\u2236': -15.828865681131282,
+	probEmit['S'] = map[rune]float64{'\u2236': -15.828865681131282,
 		'\u4e00': -4.92368982120877,
 		'\u4e01': -9.024528361347633,
 		'\u4e02': -16.522012861691227,
diff --git a/finalseg/prob_start.go b/finalseg/prob_start.go
deleted file mode 100644
index 874df72..0000000
--- a/finalseg/prob_start.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package finalseg
-
-var ProbStart = make(map[byte]float64)
-
-func init() {
-	ProbStart['B'] = -0.26268660809250016
-	ProbStart['E'] = -3.14e+100
-	ProbStart['M'] = -3.14e+100
-	ProbStart['S'] = -1.4652633398537678
-}
diff --git a/finalseg/prob_trans.go b/finalseg/prob_trans.go
index 9c9b5c8..78dc694 100644
--- a/finalseg/prob_trans.go
+++ b/finalseg/prob_trans.go
@@ -1,14 +1,14 @@
 package finalseg
 
-var ProbTrans = make(map[byte]map[byte]float64)
+var probTrans = make(map[byte]map[byte]float64)
 
 func init() {
-	ProbTrans['B'] = map[byte]float64{'E': -0.510825623765990,
+	probTrans['B'] = map[byte]float64{'E': -0.510825623765990,
 		'M': -0.916290731874155}
-	ProbTrans['E'] = map[byte]float64{'B': -0.5897149736854513,
+	probTrans['E'] = map[byte]float64{'B': -0.5897149736854513,
 		'S': -0.8085250474669937}
-	ProbTrans['M'] = map[byte]float64{'E': -0.33344856811948514,
+	probTrans['M'] = map[byte]float64{'E': -0.33344856811948514,
 		'M': -1.2603623820268226}
-	ProbTrans['S'] = map[byte]float64{'B': -0.7211965654669841,
+	probTrans['S'] = map[byte]float64{'B': -0.7211965654669841,
 		'S': -0.6658631448798212}
 }
diff --git a/finalseg/viterbi.go b/finalseg/viterbi.go
index 8413a45..7dcb2bc 100644
--- a/finalseg/viterbi.go
+++ b/finalseg/viterbi.go
@@ -5,15 +5,22 @@ import (
 	"sort"
 )
 
-const MIN_FLOAT = -3.14e100
+const MinFloat = -3.14e100
 
-var PrevStatus = make(map[byte][]byte)
+var (
+	prevStatus = make(map[byte][]byte)
+	probStart  = make(map[byte]float64)
+)
 
 func init() {
-	PrevStatus['B'] = []byte{'E', 'S'}
-	PrevStatus['M'] = []byte{'M', 'B'}
-	PrevStatus['S'] = []byte{'S', 'E'}
-	PrevStatus['E'] = []byte{'B', 'M'}
+	prevStatus['B'] = []byte{'E', 'S'}
+	prevStatus['M'] = []byte{'M', 'B'}
+	prevStatus['S'] = []byte{'S', 'E'}
+	prevStatus['E'] = []byte{'B', 'M'}
+	probStart['B'] = -0.26268660809250016
+	probStart['E'] = -3.14e+100
+	probStart['M'] = -3.14e+100
+	probStart['S'] = -1.4652633398537678
 }
 
 type Viterbi struct {
@@ -47,10 +54,10 @@ func viterbi(obs []rune, states []byte) (float64, []byte) {
 	V := make([]map[byte]float64, len(obs))
 	V[0] = make(map[byte]float64)
 	for _, y := range states {
-		if val, ok := ProbEmit[y][obs[0]]; ok {
-			V[0][y] = val + ProbStart[y]
+		if val, ok := probEmit[y][obs[0]]; ok {
+			V[0][y] = val + probStart[y]
 		} else {
-			V[0][y] = MIN_FLOAT + ProbStart[y]
+			V[0][y] = MinFloat + probStart[y]
 		}
 		path[y] = []byte{y}
 	}
@@ -61,17 +68,17 @@ func viterbi(obs []rune, states []byte) (float64, []byte) {
 		for _, y := range states {
 			vs0 := make(Viterbis, 0)
 			var em_p float64
-			if val, ok := ProbEmit[y][obs[t]]; ok {
+			if val, ok := probEmit[y][obs[t]]; ok {
 				em_p = val
 			} else {
-				em_p = MIN_FLOAT
+				em_p = MinFloat
 			}
-			for _, y0 := range PrevStatus[y] {
+			for _, y0 := range prevStatus[y] {
 				var transP float64
-				if tp, ok := ProbTrans[y0][y]; ok {
+				if tp, ok := probTrans[y0][y]; ok {
 					transP = tp
 				} else {
-					transP = MIN_FLOAT
+					transP = MinFloat
 				}
 				prob0 := V[t-1][y0] + transP + em_p
 				vs0 = append(vs0, &Viterbi{prob: prob0, state: y0})