diff --git a/python_symb/__pycache__/expr.cpython-311.pyc b/python_symb/__pycache__/expr.cpython-311.pyc
new file mode 100644
index 0000000..a46f047
Binary files /dev/null and b/python_symb/__pycache__/expr.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/fraction.cpython-311.pyc b/python_symb/__pycache__/fraction.cpython-311.pyc
new file mode 100644
index 0000000..07a9c8a
Binary files /dev/null and b/python_symb/__pycache__/fraction.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/operator_file.cpython-311.pyc b/python_symb/__pycache__/operator_file.cpython-311.pyc
new file mode 100644
index 0000000..59cbcc9
Binary files /dev/null and b/python_symb/__pycache__/operator_file.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/parse.cpython-311.pyc b/python_symb/__pycache__/parse.cpython-311.pyc
new file mode 100644
index 0000000..bce1ac4
Binary files /dev/null and b/python_symb/__pycache__/parse.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/symbols.cpython-311.pyc b/python_symb/__pycache__/symbols.cpython-311.pyc
new file mode 100644
index 0000000..60a6d73
Binary files /dev/null and b/python_symb/__pycache__/symbols.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/tools.cpython-311.pyc b/python_symb/__pycache__/tools.cpython-311.pyc
new file mode 100644
index 0000000..9c4ba3f
Binary files /dev/null and b/python_symb/__pycache__/tools.cpython-311.pyc differ
diff --git a/python_symb/__pycache__/tree.cpython-311.pyc b/python_symb/__pycache__/tree.cpython-311.pyc
new file mode 100644
index 0000000..64d3f43
Binary files /dev/null and b/python_symb/__pycache__/tree.cpython-311.pyc differ
diff --git a/python_symb/expr.py b/python_symb/expr.py
new file mode 100644
index 0000000..a8b2c4f
--- /dev/null
+++ b/python_symb/expr.py
@@ -0,0 +1,38 @@
+from __future__ import annotations
+from tree import Tree
+from operator_file import Add, Mul
+from operator_file import UnaryOperator, BinOperator
+from typing import List
+from symbols import Var
+from parse import infix_str_to_postfix
+
+
+class Expr(Tree):
+    def __init__(self, value, children=None):
+        super().__init__(value, children if children else [])
+
+    @staticmethod
+    def from_postfix_list(postfix: List):
+
+        def aux():
+            first = postfix.pop()
+            match first:
+                case int() | Var():
+                    return Tree(first)
+                case UnaryOperator():
+                    return Tree(first, [aux()])
+                case BinOperator():
+                    return Tree(first, [aux(), aux()])
+
+        return aux()
+
+    @staticmethod
+    def from_infix_str(expr_str):
+        expr_rev_polish = infix_str_to_postfix(expr_str)
+        return Expr.from_postfix_list(expr_rev_polish)
+
+
+
+
+
+
diff --git a/python_symb/fraction.py b/python_symb/fraction.py
new file mode 100644
index 0000000..8f09354
--- /dev/null
+++ b/python_symb/fraction.py
@@ -0,0 +1,131 @@
+from __future__ import annotations
+from typing import Iterable, Generator
+from tools import gcd
+
+
+class Fraction:
+    """
+    Should represent a fraction not a division
+    """
+    __slots__ = ['num', 'den']
+    __match_args__ = ("num", "den")
+
+    #todo check if num and den are part of a domain, so a/b as a meaning a gcd work well
+    #todo implement __iadd__ etc... if performance needed
+
+    def __init__(self, *args):
+        match args:
+            case num, den:
+                self.num = num
+                self.den = den
+            case x, :
+                self.num = x
+                self.den = 1
+
+    def __repr__(self):
+        return f'Fractions({self.num}, {self.den})'
+
+    def simplify_gcd(self):
+        """Simplify fraction by diving num and den by their gcd
+        return None"""
+        match self.num, self.den:
+            case int(num), int(den):
+                gcd_ = gcd(num, den)
+                self.num //= gcd_
+                self.den //= gcd_
+            # can be completed with others objects that support gcd like polynomials etc...
+
+    def simplify_to_num(self):
+        """from frac(a, 1) return a."""
+        if self.den == 1:
+            return self.num
+    def simplify_nested(self, rec=True):
+        """simplify nested fractions.
+        Fractions(1, Fractions(1, Fractions(1, Fractions(1, 2)))) -> Fractions(2, 1)
+        For one simplification step put rec=False
+
+        return None"""
+
+        def aux(fract):
+            match fract:
+                case Fraction(Fraction(a, b), Fraction(c, d)):
+                    fract.num = a * d
+                    fract.den = b * c
+                case Fraction(num, Fraction(a, b)):
+                    fract.num = num * b
+                    fract.den = a
+                case Fraction(Fraction(a, b), den):
+                    fract.num = a
+                    fract.den = b * den
+            
+            if rec:
+                num, den = self.num, self.den
+                if isinstance(num, Fraction) or isinstance(den, Fraction):
+                    aux(fract)
+
+        aux(self)
+
+    def simplify_all_(self):
+        self.simplify_gcd()
+        self.simplify_nested()
+        res = self.simplify_to_num()
+        if res:
+            return res
+
+        return self
+
+    def __add__(self, other):
+        match other:
+            case int(x):
+                return Fraction(self.num + self.den * x, self.den)
+            case Fraction(num, den):
+                result = Fraction(self.num * den + num * self.den, self.den * den)
+                return result
+        return ValueError
+
+    def __radd__(self, other):
+        return other + self
+
+    def __neg__(self):
+        return Fraction(-self.num, self.den)
+
+    def __mul__(self, other):
+        match other:
+            case int(x):
+                return Fraction(self.num * x, self.den)
+            case Fraction(num, den):
+                result = Fraction(self.num * num, self.den * den)
+                return result
+        return ValueError
+
+    def __rmul__(self, other):
+        return self*other
+
+    def __truediv__(self, other):
+        match other:
+            case int(x):
+                return Fraction(self.num, self.den * x)
+            case Fraction(num, den):
+                return Fraction(self.num * den, self.den * num)
+
+    def __rtruediv__(self, other):
+        res = self/other
+        return Fraction(res.den, res.num)
+
+
+if __name__ == "__main__":
+    a = Fraction(1, 2)
+    a += 1
+    print(a)
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/python_symb/integers.py b/python_symb/integers.py
new file mode 100644
index 0000000..cc56d3b
--- /dev/null
+++ b/python_symb/integers.py
@@ -0,0 +1,3 @@
+"""
+Python int is already an arbitrary precision integer, so we don't need to implement it.
+"""
diff --git a/python_symb/operator_file.py b/python_symb/operator_file.py
new file mode 100644
index 0000000..1c935e9
--- /dev/null
+++ b/python_symb/operator_file.py
@@ -0,0 +1,62 @@
+from __future__ import annotations
+from typing import Dict, Callable
+from symbols import Symbols
+
+
+class Operator(Symbols):
+    instances = []
+    def __init__(self, name : str, precedence: int, call: Callable):
+        super().__init__(name)
+        self.precedence = precedence
+        self.call = call
+        Operator.instances.append(self)
+
+    def __repr__(self):
+        return f'{self.name}'
+
+
+class UnaryOperator(Operator):
+    instances = []
+
+    def __init__(self, name: str, precedence: int, call: Callable):
+        UnaryOperator.instances.append(self)
+        super().__init__(name, precedence, call)
+
+    def __call__(self, expr):
+        return self.call(expr)
+
+
+class BinProperties:
+
+    def __init__(self, associativity: bool, commutativity: True,
+                 left_distributivity: Dict[str, bool], right_distributivity: Dict[str, bool]):
+
+        self.associativity = associativity
+        self.commutativity = commutativity
+        self.left_distributivity = left_distributivity
+        self.right_distributivity = right_distributivity
+
+
+class BinOperator(Operator):
+    instances = []
+
+    def __init__(self, name: str, precedence: int, properties: BinProperties, call: Callable):
+        BinOperator.instances.append(self)
+        super().__init__(name, precedence, call)
+        self.properties = properties
+
+    def __call__(self, left, right):
+        return self.call(left, right)
+
+
+AddProperties = BinProperties(True, True, {'*': True}, {'*': True})
+Add = BinOperator('+', 2, AddProperties, lambda x, y: x + y)
+
+
+MulProperties = BinProperties(True, True, {'+': True}, {'+': True})
+Mul = BinOperator('*', 3, MulProperties, lambda x, y: x * y)
+Sin = UnaryOperator('sin', 0, lambda x: x)
+
+Min = BinOperator('-', 1, AddProperties, lambda x, y: x - y)
+# Pns = UnaryOperator('()', 0, lambda x: x)
+
diff --git a/python_symb/parse.py b/python_symb/parse.py
new file mode 100644
index 0000000..da16714
--- /dev/null
+++ b/python_symb/parse.py
@@ -0,0 +1,114 @@
+from __future__ import annotations
+from typing import List, Union
+from operator_file import Add, Mul, Min, BinOperator, UnaryOperator
+from symbols import Symbols, Var
+from fraction import Fraction
+
+x, y = Var('x'), Var('y')
+
+ParenthesisLeft = Symbols('(')
+ParenthesisRight = Symbols(')')
+
+Number = Union[int, float, Fraction]
+
+name_to_symbol = {sy.name:sy for sy in Symbols.instances}
+
+print(name_to_symbol)
+
+"""
+example1 = "a + b * c + d"
+-
+example2 = 2*x+3*y*(4+sin(5))
+-
+example3 = "(a + b) * (c + -d))"
+should return Tree(Expr('*', [Expr('+', [Expr('a'), Expr('b')]), Expr('+', [Expr('c'), Expr('-', [Expr('d')])])]))
+"""
+
+
+def preprocess(expr: str) -> List:
+    """
+    Preprocesses a string expression to a list of symbols and numbers
+    :param expr: string expression
+    :return: list of symbols and numbers
+    """
+    return_list = []
+    expr = expr.strip()
+    expr = expr.replace(' ', '')
+    m = max([len(sy) for sy in name_to_symbol.keys()])
+    i = 0
+    while i < len(expr):
+        found = False
+        for j in range(m, 0, -1):
+            word = expr[i:i+j]
+            if word in name_to_symbol or word.isdigit():
+                if word in name_to_symbol:
+                    return_list.append(name_to_symbol[word])
+                else:
+                    return_list.append(int(word))
+                i += j
+                found = True
+                break
+
+        if not found:
+            raise ValueError(f'Invalid expression: {expr} at index {i}\n')
+    return return_list
+
+
+def return_to_string(expr: List) -> str:
+    """
+    Returns a string expression from a list of symbols and numbers
+    :param expr: list of symbols and numbers
+    :return: string expression
+    """
+    return ' '.join([str(sy) for sy in expr])
+
+
+def infix_to_postfix(expr: List) -> List:
+    global ParenthesisLeft, ParenthesisRight
+    """
+    Converts an infix string expression (standard) to a postfix expression (reverse polish notation)
+    :param expr: infix expression
+    :return: postfix expression
+
+    use shunting yard algorithm
+    """
+    op_stack = []
+    postfix = []
+    for sy in expr:
+        match sy:
+            case int() | float() | Fraction() | Var():
+                postfix.append(sy)
+            case _ if sy == ParenthesisLeft:
+                op_stack.append(sy)
+            case _ if sy == ParenthesisRight:
+                while op_stack[-1] != ParenthesisLeft:
+                    postfix.append(op_stack.pop())
+                op_stack.pop()
+            case UnaryOperator():
+                op_stack.append(sy)
+            case BinOperator():
+                while op_stack and op_stack[-1] != ParenthesisLeft and op_stack[-1].precedence >= sy.precedence:
+                    postfix.append(op_stack.pop())
+                op_stack.append(sy)
+    while op_stack:
+        postfix.append(op_stack.pop())
+    return postfix
+
+
+def infix_str_to_postfix(expr):
+    return infix_to_postfix(preprocess(expr))
+
+
+if __name__ == "__main__":
+
+    expr = "(x+7)*y+sin(24-2*(1-5))"
+    prep = preprocess(expr)
+    print(prep)
+    post = infix_to_postfix(prep)
+    print(post)
+    print(return_to_string(post))
+
+
+
+
+
diff --git a/python_symb/symbols.py b/python_symb/symbols.py
new file mode 100644
index 0000000..f853677
--- /dev/null
+++ b/python_symb/symbols.py
@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+
+class Symbols:
+    """
+    All maths things (other than number) that will be parsed need to be of "Symbols" class
+    """
+    instances = []
+
+    def __init__(self, name):
+        self.name = name
+        Symbols.instances.append(self)
+
+    def __repr__(self):
+        return self.name
+
+    def __str__(self):
+        return self.name
+
+
+class Var(Symbols):
+    """
+    variable, like 'x' in x+2
+    """
+    instances = []
+
+    def __init__(self, name):
+        super().__init__(name)
+        print(self.__class__)
+        self.__class__.instances.append(self)
+
diff --git a/python_symb/tools.py b/python_symb/tools.py
new file mode 100644
index 0000000..3d3b00a
--- /dev/null
+++ b/python_symb/tools.py
@@ -0,0 +1,14 @@
+from __future__ import annotations
+from typing import *
+
+
+def gcd(a, b):
+
+    if b > a:
+        return gcd(b, a)
+
+    if b == 0:
+        return a
+
+    return gcd(b, a % b)
+
diff --git a/python_symb/tree.py b/python_symb/tree.py
new file mode 100644
index 0000000..ec1a252
--- /dev/null
+++ b/python_symb/tree.py
@@ -0,0 +1,80 @@
+from __future__ import annotations
+from typing import Iterable, Generator
+from collections import deque
+
+
+class Tree:
+    """
+    Ultra generic Test class. Can be used to represent any Test structure.
+
+    value : value of the node. Can be a binary operator like "+", a ternary operator like "if", a number etc...
+
+    depth_first_order : the default order of the node in the depth first traversal. Used to implement the depth_first method.
+    0 is pre-order, 1 is in-order (for binary Test), -1 is post-order.
+    for instance to write "a ? b : c" you need to write Tree("?", [Tree("a"), Tree("b"), Tree("c")])
+    and set the depth_first_order of the "?" node to 1.
+
+    children : the children of the node. Can be empty.
+    """
+    __slots__ = ['value', 'children', 'depth_first_order']
+
+    def __init__(self, value, children: Iterable[Tree] = None, depth_first_order: int = 0):
+        self.value = value
+        self.depth_first_order = depth_first_order
+        self.children = children if children else []
+
+    def __repr__(self) -> str:
+        return f'Tree({self.value}, {self.children})' if self.children else f'Leaf({self.value})'
+
+    def height(self) -> int:
+        return 1 + max((child.height() for child in self.children), default=0)
+
+    def size(self) -> int:
+        return 1 + sum(child.size() for child in self.children)
+
+    def breadth_first(self) -> Generator[Tree]:
+
+        queue = deque([self])
+
+        while queue:
+            poped = queue.popleft()
+            for child in poped.children:
+                queue.append(child)
+
+            yield poped
+
+    def depth_first_default(self) -> Generator[Tree]:
+
+        def aux(tree):
+            n = len(tree.children)
+            if not tree.children:
+                yield tree
+
+            for i, child in enumerate(tree.children):
+                if i == tree.depth_first_order:
+                    yield tree
+
+                yield from aux(child)
+
+            if tree.depth_first_order == -1:
+                yield tree
+
+        yield from aux(self)
+
+    def depth_first_pre_order(self) -> Generator[Tree]:
+
+        def aux(tree):
+            yield tree
+            for child in tree.children:
+                yield from aux(child)
+
+        yield from aux(self)
+
+    def depth_first_post_order(self) -> Generator[Tree]:
+
+        def aux(tree):
+            for child in tree.children:
+                yield from aux(child)
+            yield tree
+
+        yield from aux(self)
\ No newline at end of file
diff --git a/python_symb/visual.py b/python_symb/visual.py
new file mode 100644
index 0000000..758d02a
--- /dev/null
+++ b/python_symb/visual.py
@@ -0,0 +1,92 @@
+import tkinter as tk
+from expr import Expr
+
+class Visual:
+    def __init__(self):
+        self.root = tk.Tk()
+        self.root.title("Visual")
+        self.root.geometry("800x800")
+
+        # Add a canvas on the left side of the window
+        self.tree_canvas = tk.Canvas(self.root, width=500, height=500, bg="white")
+        self.tree_canvas.pack(side=tk.LEFT, expand=False)
+
+        # Create right frame
+        self.right_frame = tk.Frame(self.root, width=300, height=500, background="grey")
+
+
+        # Add a label with the text "Input" on top of the right frame, should not take all the space
+        self.input_label = tk.Label(self.right_frame, text="Input (infix string):")
+
+
+        # Add a entry below the label with default text "(5+2)*3"
+        self.input_entry = tk.Entry(self.right_frame, width=50)
+        self.input_entry.insert(0, "(5+2)*3")
+
+
+
+        # Add a button below the entry with the text "To Tree"
+        self.input_button = tk.Button(self.right_frame, text="To Tree", command=self.show_tree)
+
+        # Pack the widgets, make sure they are not expanding, and all are fixed size
+
+
+        self.input_label.pack()
+        self.input_entry.pack()
+        self.input_button.pack()
+        self.right_frame.pack(side=tk.LEFT, expand=False)
+
+
+
+
+
+
+        self.root.mainloop()
+
+    def show_tree(self):
+        # Get the text from the entry
+        text = self.input_entry.get()
+
+        # Clear the canvas
+        self.tree_canvas.delete("all")
+        tree = Expr.from_infix_str(text)
+
+        # Draw the tree
+        self.draw_tree(tree)
+
+    def create_circle(self, x, y, r, color):  # center coordinates, radius
+        x0 = x - r
+        y0 = y - r
+        x1 = x + r
+        y1 = y + r
+        return self.tree_canvas.create_oval(x0, y0, x1, y1, fill=color)
+
+    def draw_tree(self, tree, first_x=250, first_y=50, x_offset=100, y_offset=100):
+
+        children = tree.children
+        n = len(children)
+        for i in range(n):
+            child = children[i]
+            x = first_x + (i - (n - 1) / 2) * x_offset
+            y = first_y + y_offset
+
+            #Link the node to the parent
+            self.tree_canvas.create_line(first_x, first_y, x, y)
+            # Draw the node
+            self.draw_tree(child, int(x), y, x_offset, y_offset)
+
+        # Draw the root node
+        self.create_circle(first_x, first_y, 20, "red")
+        self.tree_canvas.create_text(first_x, first_y, text=str(tree.value))
+
+if __name__ == "__main__":
+    Visual()
+
+
+
+
+
+
+
+
+