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"""
 6from copy import copy
 7from qiskit.quantum_info import SparsePauliOp
 8from .object import Equation, Variable
 9
10

[docs]
11def one_in_n(variables: list[int | Variable], size: int | None = None, quadratic: bool = False) -> Equation:
12    """
13    Generates Equation for One in N problem.
14
15    One in N returns True if and only if exactly one of targeted indexes in 1, and all others are 0.
16
17    Args:
18        variables (list[int  |  Variable]): Triggered variables or variable indexes
19        size (int | None, optional): Size of problem, if not given it takes the first found Variable.size value. Defaults to None.
20
21    Returns:
22        Equation: Equation returning True if exactly one of passed indexes is 1, False otherwise
23    """
24    if size is None:
25        for var in variable:
26            if isinstance(var, Variable):
27                size = var.size
28                break
29
30    eq = Equation(size)
31    new_variables = set()
32    for var in copy(variables):
33        if isinstance(var, int):
34            new_variables.add(eq.get_variable(var))
35        elif isinstance(var, Variable):
36            new_variables.add(eq.get_variable(var.index))
37
38    if quadratic:
39        for variable in new_variables:
40            eq += variable
41        I = SparsePauliOp.from_sparse_list([('I', [], 1)], size)
42        hamiltonian = I - eq.hamiltonian
43        return Equation(hamiltonian.compose(hamiltonian))
44
45    for variable in new_variables:
46        equation = variable
47        for different_var in new_variables - {variable}:
48            equation &= ~different_var
49        eq |= equation
50
51    return eq