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Dan Ghica
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SkyNet will never happen.
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Dan Ghica

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Extraordinary lecture THIS WEDNESDAY given by well known mathematical physicist and environmentalist +John Baez :
The Mathematics of Planet Earth
Wednesday, February 26th, 4pm
Haworth 101
University of Birmingham
Please propagate!
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A bit of propaganda for my student +Olle Fredriksson's beautiful paper "Distributed call-by-value machines". I am very proud of him!
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Game semantics workshop at ETAPS 2014. Abstract submission deadline is January 25. 
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Can we compute with real numbers in real time?
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I am closing comments here, kindly please comment on the blog article itself. Thanks!
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Dan Ghica

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Anyone using ResearchGate? Any good? Any point to it?
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I'll definitely not be an early adopter, but if it gets traction or provides some unique services I am open minded.
 
The programme of GALOP (Games for Logic and Programming Languages IX) is posted. See you in Grenoble!
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Looks like fun!
 
I'm giving some talks at Oxford.  If you're nearby, check 'em out!  Slides and maybe videos will show up later.

Network Theory

Nature and the world of human technology are full of networks. People like to draw diagrams of networks: flow charts, electrical circuit diagrams, signal flow diagrams, Bayesian networks, Feynman diagrams and the like. Mathematically minded people know that in principle these diagrams fit into a common framework: category theory. But we are still far from a unified theory of networks. After an overview, we will look at three portions of the jigsaw puzzle in three separate talks:

• Friday 21 February 2014, 2 pm: Network Theory: overview.

• Tuesday 25 February, 3:30 pm: Network Theory I: electrical circuits and signal flow diagrams.

• Tuesday 4 March, 3:30 pm: Network Theory II: stochastic Petri nets, chemical reaction networks and Feynman diagrams.

• Tuesday 11 March, 3:30 pm: Network Theory III: Bayesian networks, information and entropy.

All these talks will happen in Lecture Theatre B in the Computer Science Department.   I'm also giving a talk in the topology seminar on Monday 24 February, 3:30 pm - somewhere in the Maths Institute, I guess:

Operads and the Tree of Life

Trees are not just combinatorial structures: they are also biological structures, both in the obvious way but also in the study of evolution. Starting from DNA samples from living species, biologists use increasingly sophisticated mathematical techniques to reconstruct the most likely “phylogenetic tree” describing how these species evolved from earlier ones. In their work on this subject, they have encountered an interesting example of an operad, which is obtained by applying a variant of the Boardmann–Vogt “W construction” to the operad for commutative monoids. The operations in this operad are labelled trees of a certain sort, and it plays a universal role in the study of stochastic processes that involve branching. It also shows up in tropical algebra. This talk is based on work in progress with Nina Otter.

Here are maps to help you find the talks:

http://johncarlosbaez.wordpress.com/2014/02/07/network-theory-talks-at-oxford/

I thank Samson Abramsky, Bob Coecke and Jamie Vicary of the Computer Science Department for inviting me to Oxford, and Ulrike Tillmann and Minhyong Kim of the Mathematical Institute for helping me get set up at Merton College.  I'd also like to thank all my collaborators on the network theory project, especially Jacob Biamonte, Jason Erbele, Brendan Fong, Tobias Fritz, Tom Leinster, Tu Pham, and Franciscus Rebro.

The picture here is an example of Howard Odum's "Energy Systems Language".  Odum was a pioneer in studying networks in ecology back in the 1950s.  I got the picture from these course notes:

• Mark T. Brown, Emergy systems, http://www.cep.ees.ufl.edu/emergy/resources/presentations.shtml
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Great!

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Can anyone explain to me (or point me to a reference) what a "cofactor" is, in the context of BDDs? There seem to be many papers on the topic but I cannot find a clearly stated definition. They seem to take the concept for granted so it must be a well known one. ‪#‎bdd‬
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I have made a ceaseless effort not to ridicule, not to bewail, not to scorn human actions, but to understand them.
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