diff --git a/README.md b/README.md
index c27ff04..8502bae 100644
--- a/README.md
+++ b/README.md
@@ -53,3 +53,57 @@ $ make compile-noinline-<subproject>
 $ make decomp-<subproject> 
 $ make decomp-noinline-<subproject> 
 ```
+
+---
+
+# Extra: Per chi non sa cosa sono le interfacce leggere prima questo
+
+```go
+type Circle struct {
+    Radius float64
+}
+type Rectangle struct {
+    Width, Height float64
+}
+
+type Shape interface {
+    Area() float64
+    Perimeter() float64
+}
+
+func (c Circle) Area() float64 {
+    return c.Radius * c.Radius * math.Pi
+}
+func (c Circle) Perimeter() float64 {
+    return 2 * c.Radius * math.Pi
+}
+func (c Circle) Curvature() float64 {
+    return 1 / c.Radius
+}
+
+func (r Rectangle) Area() float64 {
+    return r.Width * r.Height
+}
+func (r Rectangle) Perimeter() float64 {
+    return 2 * r.Radius * math.Pi
+}
+func (r Rectangle) CornerCount() int {
+    if (r.Width == 0 && r.Height == 0) { return 0 }
+    if (r.Width == 0 || r.Height == 0) { return 2 }
+    return 4
+}
+
+func AreaOverPerimeter(s Shape) float64 {
+    return s.Area() / s.Perimeter()
+}
+
+// c1 := Circle{ Radius: 5.0 }
+c1 := Circle{ 5.0 }
+
+// r1 := Rectangle{ Width: 2.0, Height: 3.0 }
+r1 := Rectangle{ 2.0, 3.0 }
+
+AreaOverPerimeter(c1)
+AreaOverPerimeter(r1)
+```
+
diff --git a/slides.md b/slides.md
index bc23b60..02d4a83 100644
--- a/slides.md
+++ b/slides.md
@@ -136,7 +136,7 @@ return y
 
 ---
 
-#### Type Parameters & Type Sets
+#### Type Parameters
 
 ```go
 import "golang.org/x/exp/constraints"
@@ -191,16 +191,18 @@ func Min[T constraints.Ordered](x, y T) T {
 
 ---
 
+#### Type Sets
+
 ```go
-type Liter float64
+type Liter32 float32
 
-type Meter float64
+type Meter64 float64
 
-type Kilogram float64
+type Kilogram64 float64
 ```
 
 ```go
-func Min[T float64](x, y T) T {
+func Min[T float64|float32](x, y T) T {
     if x < y { 
         return x
     }
@@ -215,30 +217,47 @@ Min(a, b) // Errore
 
 ---
 
+#### Type Sets
+
 ```go
 type Liter float64
 
-type Meter float64
+type Meter64 float64
 
-type Kilogram float64
+type Kilogram64 float64
 ```
 
 ```go
-func Min[T ~float64](x, y T) T {
-    if x < y { 
-        return x
-    }
+func Min[T ~float64|~float32](x, y T) T {
+    if x < y { return x }
     return y
 }
 ```
 
 ```go
-var a, b Liter = 1, 2
+var a, b float32 = 1.0, 2.0
+Min(a, b) // Ok
+var a, b float64 = 1.0, 2.0
+Min(a, b) // Ok
+
+var a, b Liter = 1.0, 2.0
 Min(a, b) // Ok
 ```
 
 ---
 
+#### Type Sets
+
+```go
+type Float interface {
+    ~float32 | ~float64
+}
+```
+
+---
+
+#### Type Sets
+
 ```go
 package constraints