diff --git a/cli/src/repl.rs b/cli/src/repl.rs
index 3a391bc..0b07a68 100644
--- a/cli/src/repl.rs
+++ b/cli/src/repl.rs
@@ -105,7 +105,7 @@ impl Highlighter for LineHighlighter {
 
         let reg = Regex::new(
             r"(?x)
-            (?P<op>([+\-/*%^!×÷⋅∧∨ᵀ]|if|otherwise|\sand|\sor|\smod|load|exit|clear|help)) |
+            (?P<op>([+\-/*%^!×÷⋅∧∨¬ᵀ]|if|otherwise|\b(and|or|mod|true|false|not)\b|load|exit|clear|help)) |
             (?P<radix>0[box][a-zA-Z0-9]+) |
             (?P<identifier>[^!-@\s_|^⌊⌋⌈⌉\[\]\{\}⟦⟧≠≥≤⁰¹²³⁴⁵⁶⁷⁸⁹⁺⁻⁼⁽⁾₀₁₂₃₄₅₆₇₈₉₊₋₌₍₎ᵀ]+(_\d+)?)",
         )
@@ -159,6 +159,7 @@ lazy_static! {
         m.insert("<=", "≤");
         m.insert(" and", " ∧");
         m.insert(" or", " ∨");
+        m.insert(" not", " ¬");
         m.insert("*", "×");
         m.insert("/", "÷");
         m.insert("^T", "ᵀ");
@@ -194,6 +195,14 @@ impl Completer for RLHelper {
                 return Ok((pos - key.len(), vec![value.to_string()]));
             }
 
+            // If the key starts with a space, it should also be expanded
+            // if it is at the start of the line. To do this, the strings
+            // are compared with the space removed in these situations.
+            if key.starts_with(' ') && slice.len() == key.len() - 1 && slice == &key[1..] {
+                let value = &(*COMPLETION_FUNCS.get(key).unwrap())[1..];
+                return Ok((pos - (key.len() - 1), vec![value.to_string()]));
+            }
+
             let mut subscript_digits = String::new();
             for c in slice.chars().rev() {
                 if c.is_digit(10) {
diff --git a/kalk/src/analysis.rs b/kalk/src/analysis.rs
index 9120944..6505d69 100644
--- a/kalk/src/analysis.rs
+++ b/kalk/src/analysis.rs
@@ -212,7 +212,7 @@ fn analyse_expr(context: &mut Context, expr: Expr) -> Result<Expr, KalkError> {
         Expr::Var(identifier) => analyse_var(context, identifier, None, None)?,
         Expr::Group(value) => Expr::Group(Box::new(analyse_expr(context, *value)?)),
         Expr::FnCall(identifier, arguments) => analyse_fn(context, identifier, arguments)?,
-        Expr::Literal(_) => expr,
+        Expr::Literal(_) | Expr::Boolean(_) => expr,
         Expr::Piecewise(pieces) => {
             let mut analysed_pieces = Vec::new();
             for piece in pieces {
diff --git a/kalk/src/ast.rs b/kalk/src/ast.rs
index 2e13a42..8e9022e 100644
--- a/kalk/src/ast.rs
+++ b/kalk/src/ast.rs
@@ -20,6 +20,7 @@ pub enum Expr {
     Group(Box<Expr>),
     FnCall(Identifier, Vec<Expr>),
     Literal(f64),
+    Boolean(bool),
     Piecewise(Vec<ConditionalPiece>),
     Vector(Vec<Expr>),
     Matrix(Vec<Vec<Expr>>),
diff --git a/kalk/src/errors.rs b/kalk/src/errors.rs
index e135167..2e898e5 100644
--- a/kalk/src/errors.rs
+++ b/kalk/src/errors.rs
@@ -23,7 +23,7 @@ pub enum KalkError {
     VariableReferencesItself,
     PiecewiseConditionsAreFalse,
     EvaluationError(String),
-    UnexpectedToken(TokenKind, TokenKind),
+    UnexpectedToken(TokenKind, Option<TokenKind>),
     UnexpectedType(String, Vec<String>),
     UndefinedFn(String),
     UndefinedVar(String),
@@ -66,7 +66,11 @@ impl ToString for KalkError {
             KalkError::PiecewiseConditionsAreFalse => String::from("All the conditions in the piecewise are false."),
             KalkError::EvaluationError(msg) => format!("Evaluation error: {}", msg),
             KalkError::UnexpectedToken(got, expected) => {
-                format!("Unexpected token: '{:?}', expected '{:?}'.", got, expected)
+                if let Some(expected) = expected {
+                    format!("Unexpected token: '{:?}', expected '{:?}'.", got, expected)
+                } else {
+                    format!("Unexpected token: '{:?}'.", got)
+                }
             }
             KalkError::UnexpectedType(got, expected) => {
                 format!("Unexpected type. Got {:?} but expected: {:?}.", got, expected.join(", "))
diff --git a/kalk/src/interpreter.rs b/kalk/src/interpreter.rs
index 4e12a78..e25e1e5 100644
--- a/kalk/src/interpreter.rs
+++ b/kalk/src/interpreter.rs
@@ -126,6 +126,7 @@ pub(crate) fn eval_expr(
         Expr::Unit(identifier, expr) => eval_unit_expr(context, identifier, expr),
         Expr::Var(identifier) => eval_var_expr(context, identifier, unit),
         Expr::Literal(value) => eval_literal_expr(context, *value, unit),
+        Expr::Boolean(value) => Ok(KalkValue::Boolean(*value)),
         Expr::Group(expr) => eval_group_expr(context, expr, unit),
         Expr::FnCall(identifier, expressions) => {
             eval_fn_call_expr(context, identifier, expressions, unit)
@@ -209,6 +210,10 @@ fn eval_unary_expr(
 
     match op {
         TokenKind::Minus => num.mul(context, KalkValue::from(-1f64)),
+        TokenKind::Not => match num {
+            KalkValue::Boolean(boolean) => Ok(KalkValue::Boolean(!boolean)),
+            _ => Err(KalkError::InvalidOperator),
+        },
         TokenKind::Percent => num.mul(context, KalkValue::from(0.01f64)),
         TokenKind::Exclamation => prelude::special_funcs::factorial(num),
         _ => Err(KalkError::InvalidOperator),
diff --git a/kalk/src/inverter.rs b/kalk/src/inverter.rs
index fab1fff..26dd799 100644
--- a/kalk/src/inverter.rs
+++ b/kalk/src/inverter.rs
@@ -85,7 +85,7 @@ fn invert(
             arguments,
             unknown_var,
         ),
-        Expr::Literal(_) => Ok((target_expr, expr.clone())),
+        Expr::Literal(_) | Expr::Boolean(_) => Ok((target_expr, expr.clone())),
         Expr::Piecewise(_) => Err(KalkError::UnableToInvert(String::from("Piecewise"))),
         Expr::Vector(_) => Err(KalkError::UnableToInvert(String::from("Vector"))),
         Expr::Matrix(_) => Err(KalkError::UnableToInvert(String::from("Matrix"))),
@@ -391,7 +391,7 @@ pub fn contains_var(symbol_table: &SymbolTable, expr: &Expr, var_name: &str) ->
 
             false
         }
-        Expr::Literal(_) => false,
+        Expr::Literal(_) | Expr::Boolean(_) => false,
         Expr::Piecewise(_) => true, // Let it try to invert this. It will just display the error message.
         Expr::Vector(items) => items
             .iter()
diff --git a/kalk/src/lexer.rs b/kalk/src/lexer.rs
index 88d4179..13a15ec 100644
--- a/kalk/src/lexer.rs
+++ b/kalk/src/lexer.rs
@@ -25,6 +25,9 @@ pub enum TokenKind {
     LessOrEquals,
     And,
     Or,
+    Not,
+    True,
+    False,
 
     UnitKeyword,
     ToKeyword,
@@ -153,6 +156,7 @@ impl<'a> Lexer<'a> {
             '<' => build(TokenKind::LessThan, "", span),
             '∧' => build(TokenKind::And, "", span),
             '∨' => build(TokenKind::Or, "", span),
+            '¬' => build(TokenKind::Not, "", span),
             ',' => build(TokenKind::Comma, "", span),
             ':' => build(TokenKind::Colon, "", span),
             ';' => build(TokenKind::Semicolon, "", span),
@@ -324,6 +328,9 @@ impl<'a> Lexer<'a> {
         let kind = match value.as_ref() {
             "and" => TokenKind::And,
             "or" => TokenKind::Or,
+            "not" => TokenKind::Not,
+            "true" => TokenKind::True,
+            "false" => TokenKind::False,
             "mod" => TokenKind::Percent,
             "unit" => TokenKind::UnitKeyword,
             "to" => TokenKind::ToKeyword,
@@ -391,7 +398,7 @@ fn is_valid_identifier(c: Option<&char>) -> bool {
         match c {
             '+' | '-' | '/' | '*' | '%' | '^' | '!' | '(' | ')' | '=' | '.' | ',' | ';' | '|'
             | '⌊' | '⌋' | '⌈' | '⌉' | '[' | ']' | '{' | '}' | 'π' | '√' | 'τ' | 'ϕ' | 'Γ' | '<'
-            | '>' | '≠' | '≥' | '≤' | '×' | '÷' | '⋅' | '⟦' | '⟧' | '∧' | '∨' | ':' | 'ᵀ'
+            | '>' | '≠' | '≥' | '≤' | '×' | '÷' | '⋅' | '⟦' | '⟧' | '∧' | '∨' | '¬' | ':' | 'ᵀ'
             | '\n' => false,
             _ => !c.is_digit(10) || is_superscript(c) || is_subscript(c),
         }
diff --git a/kalk/src/parser.rs b/kalk/src/parser.rs
index 5861962..3a7ccc9 100644
--- a/kalk/src/parser.rs
+++ b/kalk/src/parser.rs
@@ -454,6 +454,7 @@ fn parse_exponent(context: &mut Context) -> Result<Expr, KalkError> {
     if match_token(context, TokenKind::Power) {
         let op = advance(context).kind;
         let right = Box::new(parse_exponent(context)?);
+
         return Ok(Expr::Binary(Box::new(left), op, right));
     }
 
@@ -461,9 +462,10 @@ fn parse_exponent(context: &mut Context) -> Result<Expr, KalkError> {
 }
 
 fn parse_unary(context: &mut Context) -> Result<Expr, KalkError> {
-    if match_token(context, TokenKind::Minus) {
+    if match_token(context, TokenKind::Minus) || match_token(context, TokenKind::Not) {
         let op = advance(context).kind;
         let expr = Box::new(parse_unary(context)?);
+
         return Ok(Expr::Unary(op, expr));
     }
 
@@ -511,7 +513,15 @@ fn parse_primary(context: &mut Context) -> Result<Expr, KalkError> {
         TokenKind::Pipe | TokenKind::OpenCeil | TokenKind::OpenFloor => parse_group_fn(context)?,
         TokenKind::Identifier => parse_identifier(context)?,
         TokenKind::Literal => Expr::Literal(string_to_num(&advance(context).value)?),
-        _ => return Err(KalkError::UnableToParseExpression),
+        TokenKind::True => {
+            advance(context);
+            Expr::Boolean(true)
+        }
+        TokenKind::False => {
+            advance(context);
+            Expr::Boolean(false)
+        }
+        _ => return Err(KalkError::UnexpectedToken(peek(context).kind, None)),
     };
 
     Ok(expr)
@@ -713,7 +723,7 @@ fn consume(context: &mut Context, kind: TokenKind) -> Result<&Token, KalkError>
         return Ok(advance(context));
     }
 
-    Err(KalkError::UnexpectedToken(peek(context).kind, kind))
+    Err(KalkError::UnexpectedToken(peek(context).kind, Some(kind)))
 }
 
 fn is_at_end(context: &Context) -> bool {
@@ -728,7 +738,7 @@ fn skip_newlines(context: &mut Context) {
 
 fn string_to_num(value: &str) -> Result<f64, KalkError> {
     let base = get_base(value)?;
-    if let Some(result) = crate::radix::parse_float_radix(&value.replace(" ", ""), base) {
+    if let Some(result) = crate::radix::parse_float_radix(&value.replace(' ', ""), base) {
         Ok(result)
     } else {
         Err(KalkError::InvalidNumberLiteral(value.into()))
diff --git a/web/package.json b/web/package.json
index 0c792a8..1fad995 100644
--- a/web/package.json
+++ b/web/package.json
@@ -48,8 +48,8 @@
 		"svelte-preprocess": "^4.6.1",
 		"terser-webpack-plugin": "^4.2.3",
 		"ts-loader": "^8.0.2",
-		"ts-node": "^9.0.0",
-		"typescript": "^4.1.2",
+		"ts-node": "^10.8.0",
+		"typescript": "^4.7.2",
 		"webpack": "^4.44.1",
 		"webpack-cli": "^3.3.12",
 		"webpack-dev-server": "^3.11.0"
@@ -61,4 +61,4 @@
 	"browserslist": [
 		"defaults"
 	]
-}
+}
\ No newline at end of file
diff --git a/web/src/KalkCalculator.svelte b/web/src/KalkCalculator.svelte
index 570ffab..737f02b 100644
--- a/web/src/KalkCalculator.svelte
+++ b/web/src/KalkCalculator.svelte
@@ -310,7 +310,7 @@
         let result = input;
         let offset = 0;
         result = result.replace(
-            /(?<power>\^[0-9T])|(?<brackets>\[\[)|(?<radix>0[box][a-zA-Z0-9]+)|(?<comparison>(!=|[<>]=?))|(?<html>[<>&]|(\n\s*\}?|\s+))|(?<op>([+\-/*%^!≈×÷⋅∧∨ᵀ]|if|otherwise|and|or|mod)|(?<identifier>[^!-@\s_|^⌊⌋⌈⌉≈\[\]\{\}⟦⟧≠≥≤⁰¹²³⁴⁵⁶⁷⁸⁹⁺⁻⁼⁽⁾₀₁₂₃₄₅₆₇₈₉₊₋₌₍₎×÷⋅∧∨ᵀ]+(_\d+)?)\(?)/g,
+            /(?<power>\^[0-9T])|(?<brackets>\[\[)|(?<radix>0[box][a-zA-Z0-9]+)|(?<comparison>(!=|[<>]=?))|(?<html>[<>&]|(\n\s*\}?|\s+))|(?<op>([+\-/*%^!≈×÷⋅∧∨¬ᵀ]|if|otherwise|and|or|mod|true|false|not)|(?<identifier>[^!-@\s_|^⌊⌋⌈⌉≈\[\]\{\}⟦⟧≠≥≤⁰¹²³⁴⁵⁶⁷⁸⁹⁺⁻⁼⁽⁾₀₁₂₃₄₅₆₇₈₉₊₋₌₍₎×÷⋅∧∨ᵀ]+(_\d+)?)\(?)/g,
             (
                 substring,
                 power,
@@ -395,6 +395,7 @@
                     if (substring == "/") substring = "÷";
                     if (substring == "and") substring = "∧";
                     if (substring == "or") substring = "∨";
+                    if (substring == "not") substring = "¬";
                 }
 
                 if (identifier) {