Source code for qlauncher.hampy.equations

 1"""
 2`equations` module provides additional binary operations for Hampy objects.
 3
 4It's goal is too simplify the creation of more complex problem implementations, by creating them with use of smaller ones.
 5"""
 6
 7from copy import copy
 8
 9from qiskit.quantum_info import SparsePauliOp
10
11from .object import Equation, Variable
12
13

[docs]
14def one_in_n(variables: list[int | Variable], size: int, quadratic: bool = False) -> Equation:
15    """
16    Generates Equation for One in N problem.
17
18    One in N returns True if and only if exactly one of targeted indexes in 1, and all others are 0.
19
20    Args:
21            variables (list[int  |  Variable]): Triggered variables or variable indexes
22            size (int | None, optional): Size of problem, if not given it takes the first found Variable.size value. Defaults to None.
23
24    Returns:
25            Equation: Equation returning True if exactly one of passed indexes is 1, False otherwise
26    """
27    eq = Equation(size)
28    new_variables = set()
29    for var in copy(variables):
30        if isinstance(var, int):
31            new_variables.add(eq.get_variable(var))
32        elif isinstance(var, Variable):
33            new_variables.add(eq.get_variable(var.index))
34
35    if quadratic:
36        for variable in new_variables:
37            eq += variable
38        identity = SparsePauliOp.from_sparse_list([('I', [], 1)], size)
39        hamiltonian = identity - eq.hamiltonian
40        return Equation(hamiltonian.compose(hamiltonian))
41
42    for variable in new_variables:
43        equation = variable
44        for different_var in new_variables - {variable}:
45            equation &= ~different_var
46        eq |= equation
47
48    return eq