It was for test inclusion of UTF-8 characters so we do not want to
rely on external libraries.

On Fri, Oct 27, 2017 at 1:54 PM, Steffen Märcker <merkste@web.de> wrote:
 Dear Andrew,

 I didn't find time to answer earlier. Some time ago, I was looking for a
 (MT)BDD package in ST as well. I didn't found one. So the only two options
 left are

 1) implementing a new BDD lib in ST and
 2) doing FFI to some existing lib, e.g. CUDD, Sylvan, Jinc

 I'd prefer 2) since the existing libraries are feature-rich and highly
 optimized - which took quite some time. As a bonus, a solution could
 potentially switch between those backends. The biggest hurdle, in my option,
 is memory management, since most libs use some sort of reference counting.
 And you do not want to end up with nightmarish dozens of ref(bddNode)
 deref(bddNode) in your application code (like the probabilistic model
 checker PRISM does). This introduces hard to track bugs easily. However, I
 have an idea in mind how to tackle this but I didn't found the time to put
 it into code yet.

 May I ask, which sort of application do you have in mind?

 Best, Steffen

 Am .10.2017, 07:54 Uhr, schrieb Prof. Andrew P. Black <black@cs.pdx.edu>:

 Thanks for the responses so far.  I see that I need to clarify my enquiry.

 B-Trees and BDDs are not the same.  BDDs are an efficient and compact
 representations for Boolean functions, sometimes used in SAT-solvers and
 electronics design.   The key idea is that since the output must be 0 or 1,
 you can represent any Boolean function as a tree whose depth is the same as
 the number of bits in the input.

 To make the tree small and efficient, though, you need to eliminate any
 node whose two children are the same, and to share subtrees, so that you
 really get a DAG, not a tree.  The full name for these efficient compressed
 trees is “Reduced Order Binary Decision Diagrams”, or ROBDDs.  I was hoping
 that someone else had implemented the algorithms necessary to build this
 representation.

 Because sets can be considered to be Booleans functions (true => argument
 is in the set), you can use ROBDDs to efficiently represent large sets.

 To be clear, despite the word “diagram” in the name, one is not normally
 interested in drawing the BDD — except in the documentation for the package
 ;-).  Normally, BDDs they are used to represent sets, or functions, where
 the drawing would be hopelessly large.

 The BuDDy package (http://buddy.sourceforge.net/manual/main.html) is an
 example of what I’m looking for, but unfortunately it’s in C++.

         Andrew

 On 25 Oct 2017, at 21:39 , Stephane Ducasse <stepharo.self@gmail.com>
 wrote:

 Hi andrew

 I think that Avi did a package about BDD (but I thought it was special
 binary trees) so this is probably the same.
 Did you check on Squeaksource?
 http://www.squeaksource.com/BTree.html
 If this is what you are looking for I can help porting it to Pharo.

 Stef

 On Wed, Oct 25, 2017 at 9:02 PM, Prof. Andrew P. Black <black@cs.pdx.edu>
 wrote:

 Does anyone know of a BDD — that’s Binary Decision Diagram — package
 written in Smalltalk?

        Andrew