diff --git a/search/persistent.go b/search/persistent.go
index e855437..f10dcdb 100644
--- a/search/persistent.go
+++ b/search/persistent.go
@@ -26,7 +26,7 @@ type DynamicPersistent interface {
 	Dynamic
 	AtInstant(float64) Dynamic
 	ThisInstant() Dynamic
-	ToStaticPersitent() StaticPersistent
+	ToStaticPersistent() StaticPersistent
 }
 
 // Persistable types are dynamic types, convertible to PersistentDynamic.
diff --git a/search/tree/bst.go b/search/tree/bst.go
index f5401aa..1ad282c 100644
--- a/search/tree/bst.go
+++ b/search/tree/bst.go
@@ -39,7 +39,7 @@ func (bst *BST) isValid() bool {
 
 // ToPersistent converts this BST into a Persistent BST.
 func (bst *BST) ToPersistent() search.DynamicPersistent {
-	pbst := new(PersistentBST)
+	pbst := new(FullPersistentBST)
 	pbst.instant = math.MaxFloat64 * -1
 	pbst.instants = []BSTInstant{{BST: bst, instant: pbst.instant}}
 	return pbst
diff --git a/search/tree/persistent.go b/search/tree/persistent.go
deleted file mode 100644
index ddd9549..0000000
--- a/search/tree/persistent.go
+++ /dev/null
@@ -1,102 +0,0 @@
-package tree
-
-import (
-	"github.com/200sc/go-compgeo/printutil"
-	"github.com/200sc/go-compgeo/search"
-)
-
-type PersistentBST struct {
-	instant float64
-	index   int
-	// Implicitly sorted
-	instants []BSTInstant
-}
-
-type BSTInstant struct {
-	*BST
-	instant float64
-}
-
-func (pbst *PersistentBST) ThisInstant() search.Dynamic {
-	return pbst.instants[pbst.index]
-}
-
-func (pbst *PersistentBST) AtInstant(ins float64) search.Dynamic {
-	// binary search
-	bot := 0
-	top := len(pbst.instants) - 1
-	var mid int
-	for {
-		if top <= bot {
-			if pbst.instants[bot].instant > ins {
-				bot--
-			}
-			return pbst.instants[bot]
-		}
-		mid = (bot + top) / 2
-		v := pbst.instants[mid].instant
-		if v == ins {
-			return pbst.instants[mid]
-		} else if v < ins {
-			bot = mid + 1
-		} else {
-			top = mid - 1
-		}
-	}
-}
-
-func (pbst *PersistentBST) ToStaticPersitent() search.StaticPersistent {
-	return nil
-}
-func (pbst *PersistentBST) MinInstant() float64 {
-	return pbst.instants[0].instant
-}
-func (pbst *PersistentBST) MaxInstant() float64 {
-	return pbst.instants[len(pbst.instants)-1].instant
-}
-func (pbst *PersistentBST) SetInstant(ins float64) {
-	if ins < pbst.instant {
-		panic("Decreasing instants is not yet supported")
-	} else if ins == pbst.instant {
-		return
-	}
-	bsti := BSTInstant{}
-	bsti.BST = pbst.instants[len(pbst.instants)-1].copy()
-	bsti.instant = ins
-	pbst.instants = append(pbst.instants, bsti)
-	pbst.instant = ins
-	pbst.index++
-}
-
-func (pbst *PersistentBST) Insert(n search.Node) error {
-	return pbst.AtInstant(pbst.instant).Insert(n)
-}
-func (pbst *PersistentBST) Delete(n search.Node) error {
-	return pbst.AtInstant(pbst.instant).Delete(n)
-}
-func (pbst *PersistentBST) ToStatic() search.Static {
-	return pbst.AtInstant(pbst.instant).ToStatic()
-}
-func (pbst *PersistentBST) Size() int {
-	return pbst.AtInstant(pbst.instant).Size()
-}
-func (pbst *PersistentBST) InOrderTraverse() []search.Node {
-	return pbst.AtInstant(pbst.instant).InOrderTraverse()
-}
-func (pbst *PersistentBST) Search(f interface{}) (bool, interface{}) {
-	return pbst.AtInstant(pbst.instant).Search(f)
-}
-func (pbst *PersistentBST) SearchDown(f interface{}, d int) (search.Comparable, interface{}) {
-	return pbst.AtInstant(pbst.instant).SearchDown(f, d)
-}
-func (pbst *PersistentBST) SearchUp(f interface{}, u int) (search.Comparable, interface{}) {
-	return pbst.AtInstant(pbst.instant).SearchUp(f, u)
-}
-func (pbst *PersistentBST) String() string {
-	s := ""
-	for _, ins := range pbst.instants {
-		s += printutil.Stringf64(ins.instant) + ":\n"
-		s += ins.BST.String()
-	}
-	return s
-}
diff --git a/search/tree/persistentFullCopy.go b/search/tree/persistentFullCopy.go
new file mode 100644
index 0000000..356e013
--- /dev/null
+++ b/search/tree/persistentFullCopy.go
@@ -0,0 +1,137 @@
+package tree
+
+import (
+	"github.com/200sc/go-compgeo/printutil"
+	"github.com/200sc/go-compgeo/search"
+)
+
+// FullPersistentBST is an implementation of a persistent
+// binary search tree using full copies, with each
+// instant represented by a separate BST.
+type FullPersistentBST struct {
+	instant float64
+	index   int
+	// Implicitly sorted
+	instants []BSTInstant
+}
+
+// BSTInstant is a single BST within a Persistent BST.
+type BSTInstant struct {
+	*BST
+	instant float64
+}
+
+// ThisInstant returns the subtree at the most recent
+// instant set
+func (pbst *FullPersistentBST) ThisInstant() search.Dynamic {
+	return pbst.instants[pbst.index]
+}
+
+// AtInstant returns the subtree of pbst at the given instant
+func (pbst *FullPersistentBST) AtInstant(ins float64) search.Dynamic {
+	// binary search
+	bot := 0
+	top := len(pbst.instants) - 1
+	var mid int
+	for {
+		if top <= bot {
+			// round down
+			if pbst.instants[bot].instant > ins {
+				bot--
+			}
+			return pbst.instants[bot]
+		}
+		mid = (bot + top) / 2
+		v := pbst.instants[mid].instant
+		if v == ins {
+			return pbst.instants[mid]
+		} else if v < ins {
+			bot = mid + 1
+		} else {
+			top = mid - 1
+		}
+	}
+}
+
+// ToStaticPersistent returns a static peristent version
+// of the pbst
+func (pbst *FullPersistentBST) ToStaticPersistent() search.StaticPersistent {
+	// Todo
+	return nil
+}
+
+// MinInstant returns the minimum instant ever set on pbst.
+func (pbst *FullPersistentBST) MinInstant() float64 {
+	return pbst.instants[0].instant
+}
+
+// MaxInstant returns the maximum instant ever set on pbst.
+func (pbst *FullPersistentBST) MaxInstant() float64 {
+	return pbst.instants[len(pbst.instants)-1].instant
+}
+
+// SetInstant increments the pbst to the given instant.
+func (pbst *FullPersistentBST) SetInstant(ins float64) {
+	if ins < pbst.instant {
+		panic("Decreasing instants is not yet supported")
+	} else if ins == pbst.instant {
+		return
+	}
+	bsti := BSTInstant{}
+	bsti.BST = pbst.instants[len(pbst.instants)-1].copy()
+	bsti.instant = ins
+	pbst.instants = append(pbst.instants, bsti)
+	pbst.instant = ins
+	pbst.index++
+}
+
+// Insert peforms Insert on the current set instant's search tree.
+func (pbst *FullPersistentBST) Insert(n search.Node) error {
+	return pbst.AtInstant(pbst.instant).Insert(n)
+}
+
+// Delete performs Delete on the current set instant's search tree.
+func (pbst *FullPersistentBST) Delete(n search.Node) error {
+	return pbst.AtInstant(pbst.instant).Delete(n)
+}
+
+// ToStatic performs ToStatic on the current set instant's search tree.
+func (pbst *FullPersistentBST) ToStatic() search.Static {
+	return pbst.AtInstant(pbst.instant).ToStatic()
+}
+
+// Size performs Size on the current set instant's search tree.
+func (pbst *FullPersistentBST) Size() int {
+	return pbst.AtInstant(pbst.instant).Size()
+}
+
+// InOrderTraverse performs InOrderTraverse on the current
+// set instant's search tree.
+func (pbst *FullPersistentBST) InOrderTraverse() []search.Node {
+	return pbst.AtInstant(pbst.instant).InOrderTraverse()
+}
+
+// Search performs Search on the current set instant's search tree.
+func (pbst *FullPersistentBST) Search(f interface{}) (bool, interface{}) {
+	return pbst.AtInstant(pbst.instant).Search(f)
+}
+
+// SearchDown performs SearchDown on the current set instant's search tree.
+func (pbst *FullPersistentBST) SearchDown(f interface{}, d int) (search.Comparable, interface{}) {
+	return pbst.AtInstant(pbst.instant).SearchDown(f, d)
+}
+
+// SearchUp performs SearchUp on the current set instant's search tree.
+func (pbst *FullPersistentBST) SearchUp(f interface{}, u int) (search.Comparable, interface{}) {
+	return pbst.AtInstant(pbst.instant).SearchUp(f, u)
+}
+
+// String returns a string representation of pbst.
+func (pbst *FullPersistentBST) String() string {
+	s := ""
+	for _, ins := range pbst.instants {
+		s += printutil.Stringf64(ins.instant) + ":\n"
+		s += ins.BST.String()
+	}
+	return s
+}
diff --git a/search/tree/persistent_test.go b/search/tree/persistent_test.go
index 7d2dd13..be95f1d 100644
--- a/search/tree/persistent_test.go
+++ b/search/tree/persistent_test.go
@@ -1,2 +1,64 @@
 package tree
 
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	instantInputs1 = [][]testNode{
+		{{1, 1}},
+		{{2, 1}},
+		{{3, 1}},
+		{{4, 1}},
+		{{5, 1}},
+		{{6, 1}},
+		{{7, 1}},
+		{{8, 1}},
+		{{9, 1}},
+		{{10, 1}},
+	}
+)
+
+func TestPBSTDefinedInput1(t *testing.T) {
+	tree := New(RedBlack).ToPersistent()
+	for i, ls := range instantInputs1 {
+		tree.SetInstant(float64(i))
+		for _, v := range ls {
+			err := tree.Insert(v)
+			assert.Nil(t, err)
+		}
+	}
+	for i := range instantInputs1 {
+		t2 := tree.AtInstant(float64(i))
+		for j, ls2 := range instantInputs1 {
+			if j > i {
+				break
+			}
+			for _, v := range ls2 {
+				found, _ := t2.Search(v.key)
+				assert.True(t, found)
+			}
+		}
+	}
+	for i, ls := range instantInputs1 {
+		tree.SetInstant(float64(len(instantInputs1) + i))
+		for _, v := range ls {
+			err := tree.Delete(v)
+			assert.Nil(t, err)
+		}
+	}
+	for i := range instantInputs1 {
+		t2 := tree.AtInstant(float64(len(instantInputs1) + i))
+		for j, ls2 := range instantInputs1 {
+			if j > i {
+				break
+			}
+			for _, v := range ls2 {
+				found, _ := t2.Search(v.key)
+				assert.False(t, found)
+			}
+		}
+	}
+}
diff --git a/search/tree/rb_test.go b/search/tree/rb_test.go
index fcb9364..94c25c8 100644
--- a/search/tree/rb_test.go
+++ b/search/tree/rb_test.go
@@ -191,16 +191,16 @@ func TestPredSucc(t *testing.T) {
 		tree.Insert(v)
 	}
 
-	_, v := tree.SearchUp(9.5)
+	_, v := tree.SearchUp(9.5, 0)
 	assert.Equal(t, v, compFloat(1))
-	_, v = tree.SearchDown(9.5)
+	_, v = tree.SearchDown(9.5, 0)
 	assert.Equal(t, v, compFloat(2))
 
 	t2 := tree.ToStatic()
 
-	_, v = t2.SearchUp(9.5)
+	_, v = t2.SearchUp(9.5, 0)
 	assert.Equal(t, v, compFloat(1))
-	_, v = t2.SearchDown(9.5)
+	_, v = t2.SearchDown(9.5, 0)
 	assert.Equal(t, v, compFloat(2))
 
 }