diff --git a/labs/amy_specification.pdf b/labs/amy_specification.pdf
new file mode 100644
index 0000000000000000000000000000000000000000..e89b79c4415e39c8424e9a0c93aa29752b76fda6
Binary files /dev/null and b/labs/amy_specification.pdf differ
diff --git a/labs/labs01_material/SymbolicTreeModule.scala~ b/labs/labs01_material/SymbolicTreeModule.scala~
deleted file mode 100755
index c59943667302afa485cb319606f735eb0703ae52..0000000000000000000000000000000000000000
--- a/labs/labs01_material/SymbolicTreeModule.scala~
+++ /dev/null
@@ -1,91 +0,0 @@
-package amyc.ast
-
-import amyc.utils.Positioned
-
-// Definitions of symbolic Amy syntax trees
-trait TreeModule {
-  // Common ancestor for all trees
-  trait Tree extends Positioned
-
-  // Expressions
-  trait Expr extends Tree
-
-  // Variables
-  case class Variable(name: Identifier) extends Expr
-
-  // Literals
-  trait Literal[+T] extends Expr { val value: T }
-  case class IntLiteral(value: Int) extends Literal[Int]
-  case class BooleanLiteral(value: Boolean) extends Literal[Boolean]
-  case class StringLiteral(value: String) extends Literal[String]
-  case class UnitLiteral() extends Literal[Unit] { val value: Unit = () }
-
-  // Binary operators
-  case class Plus(lhs: Expr, rhs: Expr) extends Expr
-  case class Minus(lhs: Expr, rhs: Expr) extends Expr
-  case class Times(lhs: Expr, rhs: Expr) extends Expr
-  case class Div(lhs: Expr, rhs: Expr) extends Expr
-  case class Mod(lhs: Expr, rhs: Expr) extends Expr
-  case class LessThan(lhs: Expr, rhs: Expr) extends Expr
-  case class LessEquals(lhs: Expr, rhs: Expr) extends Expr
-  case class And(lhs: Expr, rhs: Expr) extends Expr
-  case class Or(lhs: Expr, rhs: Expr) extends Expr
-  case class Equals(lhs: Expr, rhs: Expr) extends Expr
-  case class Concat(lhs: Expr, rhs: Expr) extends Expr
-
-  // Unary operators
-  case class Not(e: Expr) extends Expr
-  case class Neg(e: Expr) extends Expr
-
-  // Function/ type constructor call
-  case class Call(qname: Identifier, args: List[Expr]) extends Expr
-  // The ; operator
-  case class Sequence(e1: Expr, e2: Expr) extends Expr
-  // Local variable definition
-  case class Let(df: ParamDef, value: Expr, body: Expr) extends Expr
-  // If-then-else
-  case class Ite(cond: Expr, thenn: Expr, elze: Expr) extends Expr
-  // Pattern matching
-  case class Match(scrut: Expr, cases: List[MatchCase]) extends Expr {
-    require(cases.nonEmpty)
-  }
-  // Represents a computational error; prints its message, then exits
-  case class Error(msg: Expr) extends Expr
-
-  // Cases and patterns for Match expressions
-  case class MatchCase(pat: Pattern, expr: Expr) extends Tree
-
-  abstract class Pattern extends Tree
-  case class WildcardPattern() extends Pattern // _
-  case class IdPattern(name: Identifier) extends Pattern // x
-  case class LiteralPattern[+T](lit: Literal[T]) extends Pattern // 42, true
-  case class CaseClassPattern(constr: Identifier, args: List[Pattern]) extends Pattern // C(arg1, arg2)
-
-  // Definitions
-  trait Definition extends Tree { val name: Identifier }
-  case class ModuleDef(name: Identifier, defs: List[ClassOrFunDef], optExpr: Option[Expr]) extends Definition
-  trait ClassOrFunDef extends Definition
-  case class FunDef(name: Identifier, params: List[ParamDef], retType: TypeTree, body: Expr) extends ClassOrFunDef {
-    def paramNames = params.map(_.name)
-  }
-  case class AbstractClassDef(name: Identifier) extends ClassOrFunDef
-  case class CaseClassDef(name: Identifier, fields: List[TypeTree], parent: Identifier) extends ClassOrFunDef
-  case class ParamDef(name: Identifier, tpe: TypeTree) extends Definition
-
-  // Types
-  trait Type
-  case object IntType extends Type 
-  case object BooleanType extends Type
-  case object StringType extends Type
-  case object UnitType extends Type
-  case class ClassType(qname: Identifier) extends Type
-
-  // A wrapper for types that is also a Tree (i.e. has a position)
-  case class TypeTree(tpe: Type) extends Tree
-
-  // All is wrapped in a program
-  case class Program(modules: List[ModuleDef]) extends Tree
-}
-
-// Identifiers represent unique names in Amy
-class Identifier private(val name: String)