diff --git a/src/rsprocess/assert.rs b/src/rsprocess/assert.rs
index fe1d7b5..7aaad49 100644
--- a/src/rsprocess/assert.rs
+++ b/src/rsprocess/assert.rs
@@ -1,5 +1,8 @@
 #![allow(dead_code)]
 
+// If changing IntegerType in assert.rs, also change from Num to another
+// similar parser with different return type in grammar.lalrpop in
+// AssertExpression
 type IntegerType = i64;
 
 #[derive(Debug, Clone)]
@@ -10,126 +13,65 @@ pub struct RSassert {
 #[derive(Debug, Clone)]
 pub enum Tree {
     Concat(Box<Tree>, Box<Tree>),
-    If(Box<Boolean>, Box<Tree>),
-    IfElse(Box<Boolean>, Box<Tree>, Box<Tree>),
-    Assignment(AssignmentVar, Box<Expression>),
+    If(Box<Expression>, Box<Tree>),
+    IfElse(Box<Expression>, Box<Tree>, Box<Tree>),
+    Assignment(AssignmentVariable, Box<Expression>),
     Return(Box<Expression>),
     For(Variable, Range, Box<Tree>),
 }
 
 #[derive(Debug, Clone)]
-pub enum Expression {
-    B(Boolean),
-    A(Arithmetic),
-    Lab(Label),
-    Set(Set),
-    El(Element),
-    Str(Str),
+pub struct Variable {
+    data: String,
+}
 
-    Var(Variable), // for when the type should just be passed through
+impl Variable {
+    pub fn from(data: String) -> Self {
+	Self { data }
+    }
 }
 
 #[derive(Debug, Clone)]
-pub enum Boolean {
-    Var(Variable), // should be of type boolean
+pub enum AssignmentVariable {
+    Var(Variable),
+    QualifiedVar(Variable, QualifierRestricted)
+}
+
+#[derive(Debug, Clone)]
+pub enum Expression {
     True,
     False,
-    Not(Box<Boolean>),
-    And(Box<Boolean>, Box<Boolean>),
-    Or(Box<Boolean>, Box<Boolean>),
-    Xor(Box<Boolean>, Box<Boolean>),
-
-    Less(Arithmetic, Arithmetic),
-    LessEq(Arithmetic, Arithmetic),
-    More(Arithmetic, Arithmetic),
-    MoreEq(Arithmetic, Arithmetic),
-    Eq(Arithmetic, Arithmetic),
-    NotEq(Arithmetic, Arithmetic),
-
-    LabelEq(Label, Label),
-    LabelNotEq(Label, Label),
-
-    SetSub(Set, Set),
-    SetSubEq(Set, Set),
-    SetSuper(Set, Set),
-    SetSuperEq(Set, Set),
-    SetEq(Set, Set),
-    SetEmpty(Set),
-
-    ElEq(Element, Element),
-    ElNotEq(Element, Element),
-
-    StrEq(Str, Str),
-    StrNotEq(Str, Str),
-    StrSubstring(Str, Str),
-}
-
-#[derive(Debug, Clone)]
-pub enum Arithmetic {
-    Var(Variable), // should be of type arithmetic
     Integer(IntegerType),
-    Plus(Box<Arithmetic>, Box<Arithmetic>),
-    Minus(Box<Arithmetic>, Box<Arithmetic>),
-    Times(Box<Arithmetic>, Box<Arithmetic>),
-    Quotient(Box<Arithmetic>, Box<Arithmetic>),
-    Reminder(Box<Arithmetic>, Box<Arithmetic>),
-    Exponential(Box<Arithmetic>, Box<Arithmetic>),
-    Rand(Box<Arithmetic>, Box<Arithmetic>),
-    Min(Box<Arithmetic>, Box<Arithmetic>),
-    Max(Box<Arithmetic>, Box<Arithmetic>),
+    Label(Box<super::structure::RSlabel>),
+    Set(super::structure::RSset),
+    Element(super::translator::IdType),
+    String(String),
+    Var(AssignmentVariable),
 
-    SetLength(Set),
-    StrLength(Str),
+    Unary(Unary, Box<Expression>),
+    Binary(Binary, Box<Expression>, Box<Expression>),
 }
 
 #[derive(Debug, Clone)]
-pub enum Label {
-    Var(Variable), // should be of type label
-    Literal(Box<super::structure::RSlabel>),
-}
-
-#[derive(Debug, Clone)]
-pub enum Set {
-    Var(Variable), // should be of type set
-    Literal(super::structure::RSset),
-    Append(Box<Set>, Element),
-    Union(Box<Set>, Box<Set>),
-    Intersection(Box<Set>, Box<Set>),
-    Difference(Box<Set>, Box<Set>),
-    SimmetricDifference(Box<Set>, Box<Set>),
-    ValueOfLabel(Label, Qualifier),
-}
-
-#[derive(Debug, Clone)]
-pub enum Element {
-    Var(Variable), // should be of type element
-    Literal(super::translator::IdType),
-}
-
-#[derive(Debug, Clone)]
-pub enum Str {
-    Var(Variable), // should be of type string
-    Literal(String),
-    Concat(Box<Str>, Box<Str>),
-    ArithmeticToString(Box<Arithmetic>),
-    BooleanToString(Box<Boolean>),
-    ElementToString(Element),
-    CommonSubstring(Box<Str>, Box<Str>),
-}
-
-#[derive(Debug, Clone)]
-pub enum AssignmentVar {
-    Var(Variable),
-    ValueOfVariable(Variable, QualifierAssignment),
-}
-
-#[derive(Debug, Clone)]
-pub struct Variable {
-    name: String,
+pub enum Range {
+    IterateOverSet(Box<Expression>),
+    IterateInRange(Box<Expression>, Box<Expression>),
 }
 
 #[derive(Debug, Clone, Copy)]
-pub enum QualifierAssignment {
+pub enum Unary {
+    Not,
+    Rand,
+
+    Empty,
+    Length,
+    ToStr,
+    Qualifier(Qualifier)
+}
+
+
+#[derive(Debug, Clone, Copy)]
+pub enum QualifierRestricted {
     Entities,
     Context,
     Reactants,
@@ -141,23 +83,33 @@ pub enum QualifierAssignment {
 
 #[derive(Debug, Clone, Copy)]
 pub enum Qualifier {
-    Entities,
-    Context,
     AvailableEntities,
-
-    Reactants,
-    ReactantsAbsent,
     AllReactants,
-
-    Inhibitors,
-    InhibitorsPresent,
     AllInhibitors,
-
-    Products,
+    Restricted(QualifierRestricted),
 }
 
-#[derive(Debug, Clone)]
-pub enum Range {
-    IterateOverSet(Set),
-    IterateInRange(Box<Arithmetic>, Box<Arithmetic>),
+#[derive(Debug, Clone, Copy)]
+pub enum Binary {
+    And,
+    Or,
+    Xor,
+    Less,
+    LessEq,
+    More,
+    MoreEq,
+    Eq,
+    NotEq,
+    Plus,
+    Minus,
+    Times,
+    Exponential,
+    Quotient,
+    Reminder,
+    Concat,
+
+    SubStr,
+    Min,
+    Max,
+    CommonSubStr,
 }
diff --git a/src/rsprocess/grammar.lalrpop b/src/rsprocess/grammar.lalrpop
index a46f116..1b8a5d7 100644
--- a/src/rsprocess/grammar.lalrpop
+++ b/src/rsprocess/grammar.lalrpop
@@ -5,7 +5,9 @@ use crate::rsprocess::structure::{RSset,
 				  RSprocess,
 				  RSenvironment,
 				  RSsystem,
+				  RSlabel,
 				  RSreaction};
+use crate::rsprocess::structure::assert;
 use crate::rsprocess::translator::{Translator, IdType};
 use crate::rsprocess::presets::Instructions;
 use crate::rsprocess::presets;
@@ -120,6 +122,7 @@ Reaction: RSreaction = {
 	RSreaction::from(r, i, p),
 }
 
+
 // -----------------------------------------------------------------------------
 //                               ContextParser
 // -----------------------------------------------------------------------------
@@ -152,6 +155,7 @@ CTX_process: RSprocess = {
 	}
 };
 
+
 // -----------------------------------------------------------------------------
 //                             EnvironmentParser
 // -----------------------------------------------------------------------------
@@ -165,28 +169,154 @@ Env_term: (IdType, RSprocess) = {
 	(translator.encode(identifier), k)
 };
 
+
 // -----------------------------------------------------------------------------
 //                                AssertParser
 // -----------------------------------------------------------------------------
-// pub Assert: Box<RSassert> = {
-//     <f: Formula_Assert> => Box::new(f)
-// };
+pub Assert: Box<assert::RSassert> = {
+    "fn" "{" <f: AssertTree> "}" =>
+	Box::new(assert::RSassert{tree: f}),
+};
+
+AssertTree: assert::Tree = {
+    <t1: AssertTree2> ";" <t2: AssertTree> =>
+	assert::Tree::Concat(Box::new(t1), Box::new(t2)),
+    <t: AssertTree2> => t,
+}
+
+AssertTree2: assert::Tree = {
+    "if" <e: AssertExpression>
+    "then" "{" <t: AssertTree> "}" =>
+	assert::Tree::If(Box::new(e), Box::new(t)),
+
+    "if" <e: AssertExpression>
+    "then" "{" <t1: AssertTree> "}"
+    "else" "{" <t2: AssertTree> "}" =>
+	assert::Tree::IfElse(Box::new(e), Box::new(t1), Box::new(t2)),
+
+    "let" <v: AssertAssignmentVar> "=" <e: AssertExpression> =>
+	assert::Tree::Assignment(v, Box::new(e)),
+
+    "return" <e: AssertExpression> =>
+	assert::Tree::Return(Box::new(e)),
+
+    "for" <v: AssertVariable> "in" <r: AssertRange> "{" <t: AssertTree> "}" =>
+	assert::Tree::For(v, r, Box::new(t)),
+}
+
+AssertAssignmentVar: assert::AssignmentVariable = {
+    <v: AssertVariable> => assert::AssignmentVariable::Var(v),
+    <v: AssertVariable> "." <q: AssertQualifierRestricted> =>
+	assert::AssignmentVariable::QualifiedVar(v, q),
+}
+
+AssertVariable: assert::Variable = {
+    <v: Literal> => assert::Variable::from(v)
+}
+
+AssertExpression: assert::Expression = {
+    "(" <e: AssertExpression> ")" => e,
+    "True" => assert::Expression::True,
+    "False" => assert::Expression::False,
+
+    // If changing IntegerType in assert.rs, also change from Num to another
+    // similar parser with different return type
+    <i: Num> => assert::Expression::Integer(i),
+
+    <lab: AssertLabel> => assert::Expression::Label(Box::new(lab)),
+    <set: Set_of_entities> => assert::Expression::Set(set),
+    "'" <el: Literal> "'" => assert::Expression::Element(translator.encode(el)),
+
+    // strings
+    PATH => assert::Expression::String(<>.trim_end_matches("\"")
+					 .trim_start_matches("\"")
+					 .to_string()),
+
+    <unp: AssertUnaryPrefix> <e: AssertExpression> =>
+	assert::Expression::Unary(unp, Box::new(e)),
+    "(" <e: AssertExpression> ")" <uns: AssertUnarySuffix> =>
+	assert::Expression::Unary(uns, Box::new(e)),
+
+    "(" <e1: AssertExpression> <b: AssertBinary> <e2: AssertExpression> ")" =>
+	assert::Expression::Binary(b, Box::new(e1), Box::new(e2)),
+    <b: AssertBinaryPrefix>
+    "(" <e1: AssertExpression> "," <e2: AssertExpression> ")" =>
+	assert::Expression::Binary(b, Box::new(e1), Box::new(e2)),
+}
+
+AssertUnaryPrefix: assert::Unary = {
+    "not" => assert::Unary::Not,
+    "rand" => assert::Unary::Rand,
+}
+
+AssertUnarySuffix: assert::Unary = {
+    ".empty" => assert::Unary::Empty,
+    ".length" => assert::Unary::Length,
+    ".tostr" => assert::Unary::ToStr,
+    "." <q: AssertQualifier> => assert::Unary::Qualifier(q),
+}
+
+AssertBinary: assert::Binary = {
+    "&&" => assert::Binary::And,
+    "||" => assert::Binary::Or,
+    "^^" => assert::Binary::Xor,
+    "<" => assert::Binary::Less,
+    "<=" => assert::Binary::LessEq,
+    ">" => assert::Binary::More,
+    ">=" => assert::Binary::MoreEq,
+    "==" => assert::Binary::Eq,
+    "!=" => assert::Binary::NotEq,
+    "+" => assert::Binary::Plus,
+    "-" => assert::Binary::Minus,
+    "*" => assert::Binary::Times,
+    "^" => assert::Binary::Exponential,
+    "/" => assert::Binary::Quotient,
+    "%" => assert::Binary::Reminder,
+    "::" => assert::Binary::Concat,
+}
+
+AssertBinaryPrefix: assert::Binary = {
+    "substr" => assert::Binary::SubStr,
+    "min" => assert::Binary::Min,
+    "max" => assert::Binary::Max,
+    "commonsubstr" => assert::Binary::CommonSubStr,
+}
+
+AssertQualifier: assert::Qualifier = {
+    "AvailableEntities" => assert::Qualifier::AvailableEntities,
+    "AllReactants" => assert::Qualifier::AllReactants,
+    "AllInhibitors" => assert::Qualifier::AllInhibitors,
+    <q: AssertQualifierRestricted> => assert::Qualifier::Restricted(q),
+}
+
+AssertQualifierRestricted: assert::QualifierRestricted = {
+    "Entities" => assert::QualifierRestricted::Entities,
+    "Context" => assert::QualifierRestricted::Context,
+    "Reactants" => assert::QualifierRestricted::Reactants,
+    "ReactantsAbsent" => assert::QualifierRestricted::ReactantsAbsent,
+    "Inhibitors" => assert::QualifierRestricted::Inhibitors,
+    "InhibitorsPresent" => assert::QualifierRestricted::InhibitorsPresent,
+    "Products" => assert::QualifierRestricted::Products,
+}
+
+AssertLabel: RSlabel = {
+    "["
+       "Entities" ":" <e: Set_of_entities> ","
+       "Context" ":" <c: Set_of_entities> ","
+       "Reactants" ":" <r: Set_of_entities> ","
+       "ReactantsAbsent" ":" <r_a: Set_of_entities> ","
+       "Inhibitors" ":" <i: Set_of_entities> ","
+       "InhibitorsPresent" ":" <i_p: Set_of_entities> ","
+       "Products" ":" <p: Set_of_entities> ","
+    "]" => RSlabel::create(e, c, r, r_a, i, i_p, p)
+}
+
+AssertRange: assert::Range = {
+    "{" <e: AssertExpression> "}" => assert::Range::IterateOverSet(Box::new(e)),
+    "{" <e1: AssertExpression> ".." <e2: AssertExpression> "}" =>
+	assert::Range::IterateInRange(Box::new(e1), Box::new(e2)),
+}
 
-// Formula_Assert: RSassert = {
-//     "-" <f: Formula_Assert> => RSassert::Not(Box::new(f)),
-//     "(" <f1: Formula_Assert> "^" <f2: Formula_Assert> ")" =>
-//	RSassert::Xor(Box::new(f1), Box::new(f2)),
-//     "(" <f: Separated<Formula_Assert, "\\/">> ")" => RSassert::Or(f),
-//     "(" <f: Separated<Formula_Assert, "/\\">> ")" => RSassert::And(f),
-//     <c: Set_of_entities> "inW" => RSassert::Sub(c, RSassertOp::InW),
-//     <c: Set_of_entities> "inR" => RSassert::Sub(c, RSassertOp::InR),
-//     <c: Set_of_entities> "inI" => RSassert::Sub(c, RSassertOp::InI),
-//     <c: Set_of_entities> "inP" => RSassert::Sub(c, RSassertOp::InP),
-//     "?" "inW" => RSassert::NonEmpty(RSassertOp::InW),
-//     "?" "inR" => RSassert::NonEmpty(RSassertOp::InR),
-//     "?" "inI" => RSassert::NonEmpty(RSassertOp::InI),
-//     "?" "inP" => RSassert::NonEmpty(RSassertOp::InP),
-// };
 
 // -----------------------------------------------------------------------------
 //                                 BHMLParser
@@ -272,7 +402,9 @@ LiteralSeparatorNode: graph::NodeDisplayBase = {
 LiteralSeparatorEdge: graph::EdgeDisplayBase = {
     PATH =>
 	graph::EdgeDisplayBase::String {
-	    string: <>.trim_end_matches("\"").trim_start_matches("\"").to_string()
+	    string: <>.trim_end_matches("\"")
+		      .trim_start_matches("\"")
+		      .to_string()
 	}
 };
 
diff --git a/src/rsprocess/structure.rs b/src/rsprocess/structure.rs
index 09a2588..e7914e3 100644
--- a/src/rsprocess/structure.rs
+++ b/src/rsprocess/structure.rs
@@ -551,6 +551,28 @@ impl RSlabel {
         }
     }
 
+    #[allow(clippy::too_many_arguments)]
+    pub fn create(
+        available_entities: RSset,
+        context: RSset,
+        reactants: RSset,
+        reactants_absent: RSset,
+        inhibitors: RSset,
+        inhibitors_present: RSset,
+        products: RSset,
+    ) -> Self {
+        RSlabel {
+            available_entities: available_entities.clone(),
+            context: context.clone(),
+            t: available_entities.union(&context),
+            reactants,
+            reactants_absent,
+            inhibitors,
+            inhibitors_present,
+            products,
+        }
+    }
+
     pub fn get_context(&self) -> (&RSset, &RSset, &RSset) {
         (
             &self.available_entities,