2018-03-28

# Trivialib.Bdd

Functional implementation of (Ordered) Binary Decision Diagram (BDD) and Zero-suppressed Binary Decision Diagram (ZDD).

• Bryant, Randal E. "Graph-based algorithms for boolean function manipulation." Computers, IEEE Transactions on 100.8 (1986): 677-691.
• Minato, Shin-ichi. "Zero-suppressed BDDs for set manipulation in combinatorial problems." Design Automation, 1993. 30th Conference on. IEEE, 1993.

Tutorial slide on Symbolic Methods for Hybrid Inference, Optimization, and Decision-making at AAAI 2016, by Scott Sanner

# FEATURES

Based on structures --- moderately fast

Weak hash table --- GC-aware, moderate memory usage

Pattern matching --- functional, clean implementation

# TODOs

• more useful interfaces for set manipulation, function manipulation
• speed
• extension to ADD (Algebraic Decision Diagram) --- mostly trivial
• extension to XADD (algebraic decision diagram)
• extension to MV-DDs (multi-valued decision diagram)
• extension to AADDs (affine algebrainc decision diagram) --- for representing formula
• extension to XADDs (continuous variable extension of algebrainc decision diagram) --- for continuous range
• extension to SDD (sentensial decision diagram)

# Usage

Web API Documentation will be available at http://quickdocs.org/trivialib.bdd/

``````
;; Knuth Chapter 4, figure 12 (and 122), rightmost ("kernel")
;; represent a set {{1,3,5},{1,4},{2,4,6},{2,5},{3,6}}
(labels ((add2 (dd1 dd2) (odd-apply dd1 dd2 (lambda (a b) (or a b))))
(mul2 (dd1 dd2) (odd-apply dd1 dd2 (lambda (a b) (and a b))))
(if args
(mul (dd1 dd2 &rest args)
(if args
(apply #'mul (mul2 dd1 dd2) args)
(mul2 dd1 dd2)))
(o (x) (odd (unit x)))
(x (x) (odd (!unit x)))
(change-many (node &rest args) (reduce #'change args :initial-value node)))

(with-odd-context (:variable '(a b c d e f))
;; stored into VARIABLES slot of an ODD. ^^^
;; Different variable orderings make ODDs incompatible.
(gcprint
;; using BDD reduction rule: 15 nodes
(add (mul (o 1) (x 2) (o 3) (x 4) (o 5) (x 6))
(mul (o 1) (x 2) (x 3) (o 4) (x 5) (x 6))
(mul (x 1) (o 2) (x 3) (o 4) (x 5) (o 6))
(mul (x 1) (o 2) (x 3) (x 4) (o 5) (x 6))
(mul (x 1) (x 2) (o 3) (x 4) (x 5) (o 6)))))
(with-odd-context (:operation #'zdd-apply)
;; Different reduction rule also make ODDs incompatible.
(gcprint
;; using Zero-suppressed reduction rule: 8 nodes
(add (odd (change-many (leaf t) 1 3 5))
(odd (change-many (leaf t) 1 4))
(odd (change-many (leaf t) 2 4 6))
(odd (change-many (leaf t) 2 5))
(odd (change-many (leaf t) 3 6)))))
(with-odd-context (:operation #'zdd-apply)
;; using a utility function for ZDD
(gcprint
(add (odd (make-set '(1 3 5)))
(odd (make-set '(1 4)))
(odd (make-set '(2 4 6)))
(odd (make-set '(2 5)))
(odd (make-set '(3 6))))))
(with-odd-context (:operation #'zdd-apply)
;; using a utility function for ZDD
(gcprint
(odd (make-family '((1 3 5)
(1 4)
(2 4 6)
(2 5)
(3 6)))))))``````

## Dependencies

This library is at least tested on implementation listed below:

• SBCL 1.2.8 on X86-64 Linux 3.13.0-46-generic (author's environment)

Also, it depends on the following libraries:

alexandria by

Alexandria is a collection of portable public domain utilities.

trivia by Masataro Asai

NON-optimized pattern matcher compatible with OPTIMA, with extensible optimizer interface and clean codebase

immutabe-struct by Masataro Asai
trivial-garbage

For handling weak hash tables.

## Author

• Masataro Asai (guicho2.71828@gmail.com)