pyddlib 0.1.0

pyddlib is a Python3 library for manipulating decision diagrams (DD).

pyddlib is a Python3 library for manipulating decision diagrams (DD).

It is intended to follow (as much as possible) the notation and overall construction proposed in the following papers:

[1] Bryant, Randal E. Graph-based algorithms for boolean function manipulation. Computers, IEEE Transactions on 100, no. 8 (1986): 677-691.

[2] Brace, Karl S., Richard L. Rudell, and Randal E. Bryant. Efficient implementation of a BDD package. In Proceedings of the 27th ACM/IEEE design automation conference, pp. 40-45. ACM, 1991.

[3] Bahar, R. Iris, Erica A. Frohm, Charles M. Gaona, Gary D. Hachtel, Enrico Macii, Abelardo Pardo, and Fabio Somenzi. Algebraic decision diagrams and their applications. Formal methods in system design 10, no. 2-3 (1997): 171-206.

Install

It is required to have Python3 installed.

$ pip3 install pyddlib

Usage

Binary Decision Diagrams (BDDs)

You create BDDs from constants and variables by composing boolean functions with logical operations AND (&), OR (|), XOR (^) and NOT (-).

from pyddlib.BDD import BDD

one  = BDD.one()
zero = BDD.zero()
print("== True ==")
print(one)
print("== False ==")
print(zero)

x1 = BDD.variable(1)
x2 = BDD.variable(2)
x3 = BDD.variable(3)
print("=== x1 ===")
print(x1)

print("=== NOT x1 ===")
print(-x1)

print("=== x1 AND x2 ===")
print(x1 & x2)

print("=== x1 OR x2 ===")
print(x1 | x2)

print("=== x1 XOR x2 ===")
print(x1 ^ x2)

bdd1 = -x1 | (x2 ^ -x3)
if (bdd1 & one) == bdd1:
    print('True is the neutral element for AND operation!')

bdd2 = -(-x2) ^ (-(x1 | x3))
if (bdd2 | zero) == bdd2:
    print('False is the neutral element for OR operation!')

bdd3 = x1 & -x1
if bdd3.is_zero():
    print('You can check contradiction with is_zero() funtion!')

bdd4 = x1 | -x1
if bdd4.is_one():
    print('You can check tautology with is_one() function!')

bdd5 = -(x1 | -(x2 & -x3))
if (bdd5 ^ bdd5).is_zero():
    print('You can check equivalence with XOR!')

if (x1 & x2) == (x2 & x1):
    print('Commutative law works for boolean functions!')

if x1 & (x2 & x3) == (x1 & x2) & x3:
    print('Associative law works for boolean functions!')

if (x1 & (x2 | x3)) == ((x1 & x2) | (x1 & x3)):
    print('Distributivity law works: AND distributes over OR!')

if (x1 | (x2 & x3)) == ((x1 | x2) & (x1 | x3)):
    print('Distributivity law works: OR distributes over AND!')

bdd6 = -(x1 & -(-x2 | x3))
valuation1 = { 1: True, 2: True, 3: False }

if BDD.restrict(bdd6, valuation1).is_zero():
    print('You can evaluate the function with restrict!')

valuation2 = { 1: True }
if BDD.restrict(bdd6, valuation2) == (-x2 | x3):
    print('You can also partially evaluate the function with restrict!')

LICENSE

Copyright (c) 2017 Thiago Pereira Bueno All Rights Reserved.

pyddlib is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

pyddlib is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with pyddlib. If not, see http://www.gnu.org/licenses/