diff --git a/ufpy/__init__.py b/ufpy/__init__.py
index bd6db52..04f1c43 100644
--- a/ufpy/__init__.py
+++ b/ufpy/__init__.py
@@ -40,3 +40,7 @@ def new_func(*args, **kwargs):
 # GitHub package
 __github_version__ = '0.1'
 from ufpy.github import *
+
+# Algebra package
+__algebra_version = '0.1'
+from ufpy.algebra import *
diff --git a/ufpy/algebra/__init__.py b/ufpy/algebra/__init__.py
new file mode 100644
index 0000000..c10760e
--- /dev/null
+++ b/ufpy/algebra/__init__.py
@@ -0,0 +1 @@
+from ufpy.algebra.sets import *
\ No newline at end of file
diff --git a/ufpy/algebra/sets.py b/ufpy/algebra/sets.py
new file mode 100644
index 0000000..53496ef
--- /dev/null
+++ b/ufpy/algebra/sets.py
@@ -0,0 +1,105 @@
+from __future__ import annotations
+from os import environ
+
+from ufpy.math_op import i_generator, r_generator
+from ufpy.utils import withrepr
+
+__all__ = (
+    'USet',
+    'U'
+)
+
+from typing import Iterable, Iterator, Optional, TypeVar, overload
+
+T = TypeVar('T')
+OT = TypeVar('OT')
+
+@i_generator
+@r_generator
+class USet[T]:
+    @overload
+    def __init__(self, *values: T) -> None: ...
+    @overload
+    def __init__(self, *values: T, auto_update_U: bool) -> None: ...
+    @overload
+    def __init__(self, *, iterable: Iterable[T]) -> None: ...
+    @overload
+    def __init__(self, *, iterable: Iterable[T], auto_update_U: bool) -> None: ...
+
+    def __init__(self, *values: T, iterable: Optional[Iterable[T]] = None, auto_update_U: bool = True) -> None:
+        self.__set = set(iterable) if iterable else set(values)
+        self.__auto_update_U = auto_update_U
+        self.__update__()
+        
+    @property
+    def set(self) -> set[T]:
+        return self.__set
+    
+    @set.setter
+    def set(self, value: Iterable[T]):
+        self.__set = set(value)
+        self.__update__()
+        
+    # When USet updates (not required, that new USet must be not same that old one)
+    def __update__(self):
+        if self.__auto_update_U:
+            U(iterable=_get_U() | self)
+    
+    # Convert to other types
+    def __repr__(self) -> str:
+        return f'u{self.set if self.set else '{}'}'
+    
+    def __str__(self) -> str:
+        return repr(self.set) if self.set else '{}'
+    
+    # Iteration
+    def __iter__(self) -> Iterator[T]:
+        return iter(self.__set)
+    
+    # Or
+    def __or__(self, other: Iterable[OT]) -> USet[T | OT]:
+        return USet(iterable=set(self) | set(other), auto_update_U=self.__auto_update_U)
+
+    def __add__(self, other: Iterable[OT]) -> USet[T | OT]:
+        return self | other
+
+    # Substract
+    def __sub__(self, other: Iterable[OT]) -> USet[T]:
+        return USet(iterable=set(self) - set(other), auto_update_U=self.__auto_update_U)
+    
+    def __div__(self, other: Iterable[OT]) -> USet[T]:
+        return self - other
+    
+    # And
+    def __and__(self, other: Iterable[OT]) -> USet:
+        return USet(iterable=set(self) & set(other), auto_update_U=self.__auto_update_U)
+    
+    def __mul__(self, other: Iterable[OT]) -> USet:
+        return self & other
+    
+    # Not
+    def __neg__(self) -> USet:
+        return _get_U() - self
+
+environ["ufpy_USet_U"] = "{}"
+
+@overload
+def U(*values: T) -> None: ...
+@overload
+def U(*, iterable: Iterable[T]) -> None: ...
+
+@withrepr(lambda _: repr(_get_U()))
+def U(*values: T, iterable: Optional[Iterable[T]] = None) -> None:
+    environ["ufpy_USet_U"] = str(_get_U() + (USet(iterable=iterable, auto_update_U=False)
+                                             if iterable else
+                                             USet(*values, auto_update_U=False)))
+
+def _convert_type(s: str):
+    if "'" in s or '"' in s: return s.replace("'", '').replace('"', '')
+    elif s.replace('-', '').isdigit(): return int(s)
+    else: return s
+
+def _get_U():
+    s = environ["ufpy_USet_U"].replace('{', '').replace('}', '').replace('(', '').replace(')', '')
+    st = s.split(', ')
+    return USet(iterable=[x for i in st if (x := _convert_type(i))], auto_update_U=False)
diff --git a/ufpy/utils.py b/ufpy/utils.py
index 3d3a984..585892c 100644
--- a/ufpy/utils.py
+++ b/ufpy/utils.py
@@ -2,9 +2,12 @@
     'get_items_for_several_keys',
     'set_items_for_several_keys',
     'del_items_for_several_keys',
+    'withrepr'
 )
 
-from typing import TypeVar
+from ast import Call
+from typing import Any, Callable, TypeVar
+import functools
 
 from ufpy.typ import SupportsGet, SupportsSetItem, SupportsDelItem, AnyCollection
 
@@ -31,3 +34,22 @@ def del_items_for_several_keys(o: SupportsDelItem[KT, VT], keys: AnyCollection[K
     for k in keys:
         del res[k]
     return res
+
+# Useful decorators
+
+class __reprwrapper:
+    def __init__(self, repr, func):
+        self._repr = repr
+        self._func = func
+        functools.update_wrapper(self, func)
+    def __call__(self, *args, **kw):
+        return self._func(*args, **kw)
+    def __repr__(self):
+        return self._repr(self._func)
+
+T = TypeVar('T', bound=Callable)
+
+def withrepr(f: Callable[[T], str]):
+    def _wrap(func: T):
+        return __reprwrapper(f, func)
+    return _wrap