Remember today 2 – halting problem

In memoriam to Alan Turing (

„In computability theory, the halting problem can be stated as follows: Given a description of an arbitrary computer program, decide whether the program finishes running or continues to run forever. This is equivalent to the problem of deciding, given a program and an input, whether the program will eventually halt when run with that input, or will run forever.

Alan Turing proved in 1936 that a general algorithm to solve the halting problem for all possible program-input pairs cannot exist. A key part of the proof was a mathematical definition of a computer and program, what became known as a Turing machine; the halting problem is undecidable over Turing machines. It is one of the first examples of a decision problem.“


Remember today – Recursive Set

In memoriam to Alan Turing (

„A subset S of the natural numbers is called recursive if there exists a total computable function f such that

f(x) = 1 if xS and f(x) = 0 if xS .

In other words, the set S is recursive if and only if the indicator function 1S is computable.“

simple, isn’t it !?!

In german language:

„Entscheidbarkeit einer mathematischen Eigenschaft

In der theoretischen Informatik heißt eine Eigenschaft auf einer Menge entscheidbar (auch: rekursiv, rekursiv ableitbar), wenn es ein Entscheidungsverfahren für sie gibt. Ein Entscheidungsverfahren ist ein Algorithmus, der für jedes Element der Menge beantworten kann, ob es die Eigenschaft hat oder nicht. Wenn es ein solches Entscheidungsverfahren nicht gibt, dann nennt man die Eigenschaft unentscheidbar. Als Entscheidungsproblem bezeichnet man die Frage, ob und wie für eine gegebene Eigenschaft ein Entscheidungsverfahren formuliert werden kann.

Während die wichtigsten syntaktischen Eigenschaften von Programmen entscheidbar sind, sind nach dem Satz von Rice alle (nichttrivialen) semantischen Eigenschaften von Programmen unentscheidbar, zum Beispiel die Terminierung eines Programmes auf einer Eingabe (Halteproblem) oder die Funktionsgleichheit zweier Programme (Äquivalenzproblem).

Ursprünglich speziell für die Gültigkeit von Formeln gemeint, wird der Begriff inzwischen für beliebige Eigenschaften auf abzählbaren Mengen verwendet. Der Begriff des Algorithmus setzt ein Berechnungsmodell voraus; wenn nichts Abweichendes gesagt wird, sind die Turingmaschinen oder ein gleichwertiges Modell gemeint.“

Hamburger Akademie für Fernstudien

Microsoft goes tablet – Microsoft surface, no not the table

My first thought was – surface wasn’t that the table with multitouch ?

By the way the Microsoft surface table was a great device but a little bit pricey.

Ok a tablet has touch operation too, but it’s a bit ambiguous with the same name.

Regrettably the surface tablet isn’t available at the moment so we’ve to wait until autumn.


MetaWatch iOS compatible – now I’m in the game

Still thinking about getting one of the first generation MetaWatches since there lunch. My experiences with the eZ430-Chronos-433 convincing to get the metawatch. Today offered on TIDeals the digital and analog Watches for a very interessting price. But I seen that a new generation was lunched with still iOS compatibility. Sine my actual mobile phone is from Apple and I own two iPads the new Watch seems peferable. It’s 199 $ for the programmable smartwatch with Bluetooth 4.0 – ordered directly on

“ Dallas, TX and Espoo, Finland May 22, 2012 – Today, Meta Watch launches its new smartwatch development system featuring Bluetooth 4.0 wireless technology for connectivity and compatibility with Apple’s iPhone® 4S, iPad 3, and Android platforms. It is available for purchase immediately from the Texas Instruments Incorporated (TI) e-Store and the web site. Initial customer shipments will commence before the end of May.

Leveraging TI’s CC2564 “dual mode” solution, the Meta Watch development system supports both Bluetooth low energy technology and ‘classic’ Bluetooth wireless technology enabling it to function in many new applications.

“We are delighted to be the first company to ship a Bluetooth 4.0 smartwatch compatible with both iPhone and Android platforms” said Bill Geiser, CEO and co-founder of Meta Watch. “While our new development system will greatly expand opportunities for Meta Watch, our goal remains unchanged – to make it simple and profitable for developers to create smartwatch applications. To this end we offer a broad range of customization options for our customers. Embedded system developers can leverage our open source firmware, embedded SDK, and a free embedded programming IDE that runs on most Windows and Linux Operating Systems. Our remote protocol and API’s enable smart phone application developers to leverage their existing iOS or Android code base eliminating the need to create a new code base for a new platform. Last, but certainly not least, our supply chain and production infrastructure was created from the very beginning to scale and allow our ODM/OEM customers to get to market fast.”

Features of the Meta Watch Bluetooth 4.0 development include:

  • Case / strap: 3 ATM water resistant stainless steel leather strap (in black or white)
  • Colors: black or white
  • Display: Mirror polymer network LCD; 96×96. Fully reflective for direct sunlight
  • Lens: scratch-resistant mineral glass
  • I/O: 6 fully programmable buttons, 3 axis accelerometer, vibrating motor & an ambient light sensor
  • MCU: TI’s ultra-low-power MSP430™ microcontroller
  • Radio: CC2564 Bluetooth 4.0 transceiver; with profile support for SPP and BLE-GATT

Pricing, availability, and more

  • Availability date: May 2012
  • Unit Cost of Meta Watch Development Platform: USD $199
  • Regions shipped to: US & Europe.
  • Where to buy: and
  • Available Styles: Stainless steel case with black mask & black leather strap; stainless steel case with white mask and white leather strap
  • Latest information:

About Meta Watch
Meta Watch is a privately-held company focusing on reinventing the watch as a stylish and relevant mobile accessory. Meta Watch allows developers to quickly and easily extend the interfaces of devices and applications to the wrist. Target markets and applications include: quantified self & mobile health, messaging, alerts and notifications, carrier value added services, navigation and location-based services, mobile, and music lifestyle enhancement. Meta Watch is based in Dallas, Texas and has a R&D facility in Espoo, Finland.

Meta Watch is a trademark of Meta Watch Ltd. The Bluetooth® word mark and logos are registered trademarks owned by Bluetooth SIG, Inc. and any use of such marks by Meta Watch Ltd. is under license. Other trademarks and trade names are those of their respective owners.“


Keep in mind today:

“ In computer science, BNF (Backus Normal Form or Backus–Naur Form) is one of the two [1] main notation techniques for context-free grammars, often used to describe the syntax of languages used in computing, such as computer programming languages, document formats, instruction sets and communication protocol; the other main technique for writing context-free grammars is the van Wijngaarden form. They are applied wherever exact descriptions of languages are needed: for instance, in official language specifications, in manuals, and in textbooks on programming language theory.

Many extensions and variants of the original Backus–Naur notation are used; some are exactly defined, including Extended Backus–Naur Form (EBNF) and Augmented Backus–Naur Form (ABNF).

A BNF specification is a set of derivation rules, written as

<symbol> ::= __expression__where <symbol> is a nonterminal, and the __expression__ consists of one or more sequences of symbols; more sequences are separated by the vertical bar, '|', indicating a choice, the whole being a possible substitution for the symbol on the left. Symbols that never appear on a left side are terminals. On the other hand, symbols that appear on a left side are non-terminals and are always enclosed between the pair <>.

The ‚::=‘ means that the symbol on the left must be replaced with the expression on the right“