Thursday, April 02, 2015

Fundamentals volume 2 --- chapter 7 is done

Wow, it's been such a long time since I posted updates.  Surely a lot of stuff has been going on since December 2012, but still!

I found a new editor and the teamwork is great.  Since none of volume 2's text had been edited, the first order of business was to review the ~200 extant pages.  This took a while, but I'm really happy because we ended up deleting roughly 15 pages --- and that's the net effect, because I added some extra material as I went through the text too.

Not long ago we started reviewing chapter 7, and a few weeks ago we finally got to the tip of the written text.  And now, all the text for chapter 7 ("On Threading") is basically done.  The exercises include real gems.  But there are "only" 27 of them right now, so who knows... I might add more over time :).

Chapter 8, "On Recursion", is next.  Reviewing my notes for the chapter was exciting, there is a lot of new material I haven't talked about yet!

The draft is at 204 pages.

Thursday, March 19, 2015

Camp Smalltalk PDX, August 20-23

A small group of Smalltalkers have been discussing the possibility of having a Camp Smalltalk in Portland Oregon, August 20-23.  If you think you might be interested in attending such a gathering, please let us know filling our short survey.  We also encourage you to join the SCONA mailing list here.

The proposed format is:

* Thursday 20th evening prior: An informal welcoming dinner at a local pub or similar.

* Friday 21st morning - Sunday 23rd afternoon: The event proper, consisting of a blend of scheduled talks or discussions and free-form pair programming.

* Sunday 23rd evening - Farewell dinner.

The whole event is envisioned as being informal enough that showing up for only part of the time is perfectly acceptable.

Your responses will help us with our planning efforts.  Feel free to forward this message to any other Smalltalk forums or individual Smalltalkers you think might be interested.

Saturday, December 27, 2014

3x+1 and T^n(k)'s evaluation matrix

In previous posts I've been talking about the 3x+1 problem and the fabulous T(x) function that satisfies

T^n(k2^n + r) = k3^j + T^n(r)

If you let 0 <= r < 2^n, and evaluate T^m(x) for all the resulting values, and for 1 < m <= n, you get a so-called evaluation matrix.  In this evaluation matrix, such as the one below,
  • 16k + 0    8k + 0    4k + 0    2k + 0    1k + 0
  • 16k + 1    24k + 2    12k + 1    18k + 2    9k + 1
  • 16k + 2    8k + 1    12k + 2    6k + 1    9k + 2
  • 16k + 3    24k + 5    36k + 8    18k + 4    9k + 2
  • 16k + 4    8k + 2    4k + 1    6k + 2    3k + 1
  • 16k + 5    24k + 8    12k + 4    6k + 2    3k + 1
  • 16k + 6    8k + 3    12k + 5    18k + 8    9k + 4
  • 16k + 7    24k + 11    36k + 17    54k + 26    27k + 13
  • 16k + 8    8k + 4    4k + 2    2k + 1    3k + 2
  • 16k + 9    24k + 14    12k + 7    18k + 11    27k + 17
  • 16k + 10    8k + 5    12k + 8    6k + 4    3k + 2
  • 16k + 11    24k + 17    36k + 26    18k + 13    27k + 20
  • 16k + 12    8k + 6    4k + 3    6k + 5    9k + 8
  • 16k + 13    24k + 20    12k + 10    6k + 5    9k + 8
  • 16k + 14    8k + 7    12k + 11    18k + 17    27k + 26
  • 16k + 15    24k + 23    36k + 35    54k + 53    81k + 80
there are various k 2^a 3^b + r expressions.  I just proved that all such expressions satisfy 0 <= r < 2^a 3^b.  In other words, T^m(r) is the remainder of dividing T^m(x) by the corresponding 2^a 3^b.

Sunday, December 14, 2014

Smalltalks 2014 videos now available

All Smalltalks 2014 videos are now available here.  Enjoy, and happy holidays!

Tuesday, October 28, 2014

Smalltalks 2014 conference schedule

Hello from FAST.  Smalltalks 2014's schedule is now available at our website.  We are very pleased with this year's strong program.  See you at the conference!

Monday, September 08, 2014

Smalltalks 2014 invitation

1. Invitation.

The Fundación Argentina de Smalltalk (FAST, http://www.fast.org.ar) invites you to the 8th International Conference on Smalltalk Technologies (Smalltalks), to be held from November 5th through November 7th at the Universidad Tecnológica Nacional, Facultad Regional Córdoba, located in the city of Córdoba, Argentina. Everyone, including teachers, students, researchers, developers and entrepreneurs, are welcome as speakers or attendees.

This year, we are extremely happy to announce Allen and Rebecca Wirfs-Brock will attend the conference. Allen was instrumental in developing Digitalk's Visual Smalltalk, as well as a leader in modular Smalltalk design. Rebecca created the field of Responsibility Driven Design, which spawned a variety of modern disciplines such as TDD and BDD. Their presence is just a preview of an oustanding presentation program you cannot afford to miss.

2. Registration.

Registration is free and now open at

http://www.fast.org.ar/smalltalks2014.

Please make sure to register early to receive the conference's shirt, as well as to help us plan the conference's social events.

We are accepting donations from participants to help fund the conference's costs. Please see the Donate section at FAST's website,

http://www.fast.org.ar/smalltalks2014/donate.

Contributions are greatly appreciated, and can be received both in pesos for local attendees, as well as via Paypal for those coming from abroad. Please note that donors, including those that have already sent us their contribution (thank you!), will receive a set of thank you gifts as well as the conference's shirt. For those of you that need a receipt, we can provide those on site.

3. Sponsors.

In addition our generous attendee donation contributors, we would like to thank our sponsors. We would not be able to organize the conference without their help.

Platinum sponsors:
+ Caesar Systems
+ ESUG
+ GemTalk Systems
+ Instantiations

Silver sponsors:
+ InfOil

Bronze sponsors:
+ 10 Pines
+ Arduino Software
+ Mercap
+ Precision System Design
+ Smallworks

Moreover, this year our official airline carrier is Aerolineas Argentinas. To book plane tickets with Aerolineas Argentinas, please go to

http://www.aerolineas.com.ar/Congresos

and select Smalltalks 2014 from the list of events (available soon).

4. Call for participation.

Talk proposal submission for the Industry Track is now open at our website:

http://www.fast.org.ar/smalltalks2014/technical-session

If you need special arrangements (e.g. because you would like to hold a workshop session), please indicate so in the abstract. The Industry Track's submission deadline is October 13th.

Abstract submitters: please send us a photo and a short bio by answering to this email.

5. Related events.

For more information about related events, such as a Pharo Sprint or talks and presentations around the dates of the conference, please visit

http://www.fast.org.ar/smalltalks2014/events

In particular, we like to invite to you Squeakfest 2014, to be held at the same conference site on from November 3rd through November 4th. This companion event highlights Squeak and Etoys used in the context of education. To register, please go to the SqueakFest page under the related events for Smalltalks 2014.

We will update related event information as we get closer to the conference, so please check for updates.

For any additional questions please reply to this email.

See you in Córdoba!

Saturday, August 23, 2014

While at the Seaside Sprint...

Philippe Marschall had an interesting problem to think about... suppose you have a dictionary with string keys, and that you make sure the keys are uppercase.  Alas, when the code receives queries, it gets lowercase keys.  Fixing this requires sending asUppercase, which takes time.  Can you find a way such that both at: and at:put: can be made to work without sending asUppercase?  Can you do it without creating new classes?

I got a proof of concept to run 2x faster.  From what I hear, the improved code will help speed up HTTP requests.

Exceptions fixed in Squeak, Pharo and Cuis

Martin McClure just integrated the Pharo exceptions fix we worked on during Camp Smalltalk.  I imagine this fix, in 5 slices, should be straightforward to port to Squeak and Cuis.

Update: I ported the Pharo fix to Cuis.

About ESUG 2014

What a lovely conference, I'm glad to be back.  I really enjoyed the talks, you should go to the YouTube playlist and take a look.  Some that come to mind are Eliot Miranda's Spur talk, Clement Bera's talks about adaptive optimization, Tim Rowledge's talk on his work on Scratch, and Boris Shingarov's talk about modern problems for the Smalltalk VM in the IWST track, as well as Yuriy Tymchuk's presentation on Smalldromeda and Alexandre Bergel's Roassal presentation.  This is hardly a fair list though, so please excuse my brevity in favor of ESUG's video playlist.

I am also glad my Retrospective presentation was well received.  The results earned compliments from Tudor Girba.  There were plenty of laughs during the talk, and it was a lot of fun :).

More news to come...

Monday, August 11, 2014

3x+1 over the weekend

You will recall from my previous 3x+1 posts that using

T^n(q2^n + r) = q3^j + T^n(r)

one could build an evaluation matrix for each 0 <= r < 2^n.  For a long time, I had strong circumstantial evidence that the proportion of evaluation matrix rows satisfying T^n(k) > k tended to shrink as n grew.  It's so unsatisfying to merely feel something has to be true...

I am happy now, though.  After reading Concrete Mathematics for several hours, I managed a tentative proof showing the proportion of rows satisfying the growth inequality tends to zero as n goes to infinity.  If you are interested, send me a note --- there is no way I am typesetting that heavy math in this blog post!