Sunday, 24 July 2016

sequestering carbon, several books at a time LXI

The latest batch:

These include the proceedings of the UCNC conference I recently attended.  Several others are a birthday present.  (I also got a mug featuring the BBC Micro Owl logo, and a Hubble Deep Field throw.)

Friday, 22 July 2016

does anyone even remember what "VHS" stands for?

I saw them come.  I saw them go.

Japan 'to stop making VCR machines'

VCRs were used to play and record onto VHS cassettes

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Wednesday, 20 July 2016

"I did not over think it. I thought it through."

The Narcissism Of Motherhood:
Being a mother is not a job. If it were a job there’d be a selection process, pay, holidays, a superior to report to, performance assessments, Friday drinks, meetings and you could resign from your job and get another one because you didn’t like the people you were working with.

[via Danny Yee's blog]

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Monday, 18 July 2016

remember remember the 9th of November


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Sunday, 17 July 2016

a second Brexit riposte roundup

Here are my Google+ posts on the Brexit fallout I made over the couple of weeks I was away at conferences.

Brexit was a con : Referendum information: 1293 words on Brexit, v 670 pages for Scottish Independence.  "An informed electorate" my hat.

Professor A C Grayling’s letter to all 650 MPs urging Parliament not to support a motion to trigger Article 50 of the Lisbon Treaty, 1 July 2016.  Well said.

"Cat, what's your opinion on the UK leaving the EU?"  Sometimes you just have to laugh.

Boris Johnson made foreign secretary by Theresa May.  WTF?!  I've been having this really surreal dream for about 3 weeks now.  It's worse than Alice in Wonderland, the bizarre things that keep happening.  I'd like to wake up, now, please.

Everything you need to know about Theresa May’s Brexit nightmare in five minutes.  It's even worse than I thought:
You mean we can't negotiate any trade deals, inside or outside the EU, while the two-year Article 50 process is ongoing?
Exactly. Actually, it's against the law for EU member states (we'd still be an EU member state until the end of the two-year process) to conduct bilateral trade negotiations with other member states or countries.

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Friday, 15 July 2016

UCNC day 5

The final (half) day of UCNC in Manchester.

The last invited speaker of the conference was Steve Furber, talking about the SpiNNaker project (SpiNNaker stands for  "Spiking Neural Network Architecture").  After some interesting historical context, he told us of the SpiNNaker machine: one million processors in an asynchronous spiking architecture.  The preliminary machine, with 500,000 cores, was launched 30 Mar 2016, and more cores have been added since.  It can be programmed in the Python PyNN language.  For example, 165 lines of Python are needed for a Sudoku solver, where the neuronal groups inhibit other groups with the same integer value in the the same row, column, or 3x3 cell.  Once a solution has been found, the inhibitory links decrease, and the spiking rate goes up, solving a "diabolical" puzzle in about 10 seconds.  This isn't just a toy: it is representative of complex constraint problems.  So far people have only been running small programs, as they think how to scale up their ideas.  Although each core is a standard processor, exploiting the asynchronous spiking communication requires a different way of thinking.

Then on to the final technical session.  First was a talk on "Model-Based Computation"; an attempt to extend the definition of analogue computation (which implements a model analgous to the problem) in a way that can cover more of unconventional computation.  Then a couple of mathematical talks about chemical reaction system formalisms.  The first, "Towards Quantitative Verification of Reaction Systems" encoded the system in a formal solver to prove properties.  The next, "Reachability Problems for Continuous Chemical Reaction Networks" looked at proving safety properties in systems with continuous values of reactant concentrations.  The final talk was on "Global Network Cooperation Catalysed by a Small Prosocial Migrant Clique", looking at evolutionary game theory in networks with no global knowledge, and how a small clique of cooperators migrating into a network of defectors could change it to a network of cooperators.

So, another conference ends.  Next year, in Arkansas.

After two solid weeks of travel and listening, my brain is full of exciting science, and I need a lot of sleep!  I'm looking forward to getting home for a bit of a rest.

Thursday, 14 July 2016

UCNC day 4

UCNC day 4, with an embarrassment of riches in the form of invited talks.

We kicked off with an invited talk from Friedrich Simmel on “Chemical Communication Between Cell-Sized Reaction Compartments”. This was a fascinating account about a series of experiments sending signals between cells, droplets, and “genelets” (droplets containing cellular “naked” genetic machinery), based on the ideas of quorum sensing: when a high enough chemical signal concentrations is produced, because there are enough producers around, it invokes a response. We saw droplets signalling the chemicals, inducing bacteria to react, and that signal propagating through multiple droplets. Apparently there is a “bacterial Turing test”: can you make a droplet that a bacterium will interact with (through chemical signals) just as if it were another bacterium? These systems pass it. Through a clever use of microfluidics, we saw videos of sheets of bacteria interacting, via fluorescent protein production. The fluorescence increases both due to the being switched on by the signalling, and due to the bacteria reproducing, two process with similar timescales. The possibilities of this approach include forming spatial and temporal patterns through reaction-diffusion systems of interacting genetically programmed droplets. If all this wasn’t enough, Simmel finished his talk with a description of using electron lithography to etch chips, deposit gene-length strands of DNA in a controlled manner, which could then be manipulated to stick together (condense) into linear bundles. It’s early days yet; next on the agenda is using gene expression to control the condensation. Heady stuff!

Next was the workshop on Physics and Computation. Gilles Dowek started with an invited talk on “Quantitative Informational Aspects in Discrete Physics”. Gandy has shown that if a system (1) is homogeneous in space and time; (2) has a bounded speed of information transport; (3) has a bounded density of information, then it can be simulated by a cellular automaton. Since physics appears to satisfy these properties, it should be so simulable. Then came a short but necessary digression on Planck’s constant. The physical constant c has the dimensions of a speed, and it is the speed of light. Planck’s constant has the dimension of an action; what action is it? After a bit of discussion, it turns out that it is (a small multiple of) the area of a bit of information (in a particular choice of units where everything has a dimension that is some power of length) as given by the Bekenstein bound. Then Dowek went through how to build a CA in Newtonian physics, special relativity, and general relativity, that models free fall (subject to some assumptions. It can’t be done in Newtonian physics, because there is no bound on speed. In SR it can be done, with particles that contain 320 bits of information (using the Planck area); in GR they only need 168 bits. This is an existence proof, but the CAs defined are not very satisfactory, for several reasons. The task is to do better! Listening to this, I recalled Randal Beer’s Game of Life talk from ALife last week: looking at a CA in terms of processes rather than cells gives a much more natural formulation. I wonder if that would work here? 

Then we had a talk about “The Information Content of Systems in General Physics Theories”. The idea here is to look at a broad range of probabilistic theories, of which quantum mechanics is one instance. Investigating their computational complexity of the “advice” given by a physical system can shed light on what makes QM special, different from just a general theory.

After lunch Ana BelĂ©n Sainz gave an invited talk on “Postquantum Steering”. This was in the same vein as the previous talk: look at a general theory, then compare with QM. Here the idea was applied to one particular kind of system: how much can Bob “steer” distant Alice’s state, by making measurements on his own state?

Next came some more talks. The first, on “Sequent Calculus Representations for Quantum Circuits”, was an approach to making reasoning about quantum circuits look like proof theoretic reasoning in other branches of computer science, by finding an appropriate set of axioms. Next was a talk on “Physical Computation, P/poly and P/log*”, looking at the computational complexity of physical computing as an unconventional co-processor, in terms of its advice complexity. After coffee we had a talk on “Local Searches Using Quantum Annealers: How to Beat Noise and Take Advantage of the Classical Algorithms we Already Have, or, Modernising Quantum Annealing using Local Search”. This contrasted classical simulated annealing, including its two improvements of parallel tempering and population annealing, with the quantum version: quantum annealing. Each has is strengths and weakeness; here was a suggestion of how to use the quantum annealing as a “subroutine”, getting the best of both approaches. The final workshop talk was on “Quantum Probability as an Application of Data Compression Principles”, a philosophical look at probabilities in general, and branching world probabilities in particular.

The day was then completed with a further invited talk, Bob Coecke talking “In Pictures: From Quantum Foundations to Natural Language Processing”. He zipped through a beautiful, formal, diagrammatic notation for quantum systems, and how the power of this notation makes many complicated quantum puzzles ad proofs essentially vanish. There will be a book, Picturing Quantum Processes, from Cambridge University press covering this published soon.  It's 922pp: pictures take a lot of space!  After all this the quantum mechanics, he went off in an unexpected direction, by showing how the very same notation could be used to calculate the meaning of sentences from their underlying grammar and the meaning of the individual words. Some modern meaning systems use high dimensional vectors to encapsulate word meanings. Adding the grammar via the diagrams improves the calculated meaning enormously. Thinking about the mathematical structures needed leads to the suggestion of using density matrices rather than vectors, to cope with ambiguous meanings. I love this kind of work: a deep piece of work in one domain that is not only applicable in a seemingly unrelated domain, but that suggests advances there, too.