Friday, July 03, 2020

net values gross laws

there are a bunch of laws of the value, or utility of a network - all these assume a set of n nodes (presumably owned each by one user), all effectively connected to all other users. That doesn't mean there is a "full mesh" network (with n^2 links) - just the capability of communication from each to every other node. 

i'm not stuck on any particular "layer" of communications here - for those not familiar with the marvellous seven layer model of communications (or variants) we could be talking about physical or internet or application layer here - if you like, we're talking wires, versus who's in your contact list, versus who you can get to on facebook or zoom or whose blog you can read, etc

Lets leave aside annoying things like NATs (and ADSL and most cellular links) that are asymmetric - there are workarounds for that anyhow. Well, let's not leave that aside, as asymmetry of a communications service is part of why there are different laws. this matters, as constraints on who you can talk to aren't just about censorship. they create "walled gardens" - a phrase I hate as the implication is that all is well in the garden : it isn't - there's no supply of water or seeds or bees or anything to keep the garden alive. it isn't a garden. its a desert. facebook is a desert. or an elephants graveyard, where old things go to die.


metcalfe's law 
n^2
so if you have a network of 12 people, its utility is 144
since that's the total number of connections possible - for each of the 12 people, 
they can talk to 12 other people. They may not want to, but they could. I think metcalfe was getting at something more nuanced than this - I think he has been a proponent of super-linear economic growth that underpinned some teechno-evangelism from the left coast. I like it because it captures an essential idea of the Internet inherrent in always on, always reachable, and extensible. Anyone could run a server. anyone could write a server. my interpretation of this model is that it is about affordance of the capability of endless addition of new applications from anyone anywhere anytime, that anyone else can use.

reed's law
2^n
so if you have a network of 12 people, its collective potential is 4096
since thats the set of all possible subsets of people that can form.
I think reed took the same interprretation that I have, but is even more enthusiastic, but at the same time, captures the idea that new applications may be of niche interest.  the value of the network in both metcalfe and reed's models is a value that accrues to all the users - providers ('lower levels') cannot explicit this value in the same scale, because that would kill the incentive for people to create all these new apps - the entry cost would be too high, the return too low. there is no tax levy on service that could be set which would do anything else. kill the goose that laid the golden egg. I'd note that there's still a golden egg (see next laws) because more people still means more revenue as each still pay a recurrent fee, and more apps may mean more bandwidth so capacity deployed still always (in the end) will make money.

briscoe's law
n*log(n)
with a network of 12 people, your service utility is 29.82 (approx)
briscoe's taking a plausible model which I think is more about revenue  that can be made by a serrvice provider, offereing connectivity to a higher layer. Note it is still super-linear, and I am not completely convinced this makes sense.

jon's complaint (sarnoff's law)
n
so with a network of 12 people, the provider's service is worth 12 units. sarnoff devised this for broadcast networks. Broadcast systems are massively asymmetric - there's a broadcaster (often using radio/tv/satellite etc) that reaches a lot of people. hHey often get in the business of content creation (or at least sponsorship - e.g. for sports, but nowadays, for internet streaming/download too - Amazon, Netflix join the BBC, Disney etc  - securing their supply chain, etc)

I'm going to try to explain why  these are all not wrong, although, like many models, they may or may not be useful.

I claim that the internet is mostly behaving like Sarnoff's law now. we can't create new services. Not because of network effects (people on old services can't shift to the new one is not a strictly correct barrier - people went from myspace to facebook, from twitter to tiktok, but they had to do so additively. not multiplicatively - having 10 social networks or 10 video conferencing apps is 100 times less valuable than having 1 that reaches all the people that are divided by those barriers. (insert old joke about america and england being two great nations divided by a common language).

the cost of writing a new app, creating a new service is tiny. it immediately would get value if  it was possible to deploy, but long gone are the days of Metcalfe or Reed's idealised Internet. barriers to deployment exist at all levels. the wires are not open, the address books are not all equal. Apps to not afford access to other apps the way email and the web permitted arbitrary extensibility and innovation.

what's more, the stultification of the growth in new systems that can reach anyone and everyone also means that the very bottom of the system, the wires, where there is never any hope of getting more value than n for n users, is getting less. that is a great example of the poisoning of the geese.

...and they aren't laws, they are models...

I'm going to try to explain why  these are all not wrong, although, like many models, they may or may not be useful.

Tuesday, May 26, 2020

Laissez-faire pandemic management - nudge fudge

The UK government has engaged in a series of psychological games with the population, instead of actually taking effective action.

Early on, an attempt to get people to socially distance was offset by the failure to enforce the shutdown of large gatherings at sporting events such as the Cheltenham Festival or football and rock music venues. Eventually, the footie community, as well as hotel chains and theatres, voluntarily closed before the government made it mandatory, presumably out of respect for their staff & customers. This may have cost them dear in some cases, as the insurance companies may decide that since it wasn't legally enforced, cancellation costs may not be covered in many cases. Similar attempts to assume it was someone else's problem - The NHS will get its own PPE and ventilators as if by magic; someone else will decide if people maybe should wear masks in public; perhaps the evidence on what constitutes early onset warning symptoms like loss of taste and smell aren't necessary to list just yet; sure, care homes will have their own safe procedures and equipment, just like hospitals, no? and sending people there from hospitals makes total sense.

Then there was the drift into an increasingly ill-specified lockdown, with many vectors for infection (e.g. London underground&busses, all international airports) completely open - i mean for heavens sakes, if the infection isn't spread by people packed into trains and planes like sardines, when not in their own homes or workplaces, how do they think it got from Wuhan to Wolverhampton? Or Downing Street to Durham?

On that last point, the latest nudge was clearly an underhand means to break lockdown early, without bothering with the unseemly debate between  people that actually care about the loss of life due to a second wave of infection, and the people who care about loss of revenue because of the economic slowdown that lockdown has imposed.

Ironically, the economic damage was mostly caused by the total failure to show any steel will power and take early action, which would have not only saved a lot of lives, but meant we could have been cleanly, honestly, and safely out of lockdown weeks ago.

The government have become the enemy of the people, both for our health and for our wealth. Given their alleged politics, that is quite an achievement.  I'm not a conspiracy theorist. I think it is because we have a system of finding elected representatives that selects for the utterly inadequate.

Thursday, May 14, 2020

Re-identifying your social network from contact trace&test decentralised apps

Obviously, some people are uncomfortable about the app that holds your contact data for the purposes of helping warn people they may have been infected, so have devised decentralised apps to achieve same goal. however, they kind of miss the obvious. 

There's no point in the app unless people act on notifications. acting entails i) isolating ii) getting tested so if negative, can stop isolating as soon as possible. if positive, can get treatment.

If you don't want to act on notifications, don't run the app.

So now what happens when a contactee is tested?


A simple re-identification of people is do-able 
if the case rate is low and largely localized.

So if patient A is first new person on day D tested +ve in city C, and then their set of decentralized possibly infected folks F are notified and  go and get tested, and say this shuts down the outbreak, then the testing agency knows that the set of F people are contacts of A. It doesn't get too much harder to do this probalistically if there's a slightly bigger outbreak with a few As and Fs in a city/locale, based on timing...

If the case is high and not localized, contact tracing and testing has failed, and we are in a second wave. and there are lots more dead people.

So centralised or decentralised, you have to trust the test center people. who (in the NHS case) are basically the same people.

Saturday, May 09, 2020

My home's too smart for me...

We had the builders in. It started when an old cooker broke - having fixed it twice, i though, lets just redo the kitchen. then we thought, why not extend it into the garden a bit so its lighter and so it began.

Firstly, an architect, and party wall agreements.

Then engineer survey says that the 10m eucalyptus tree in our garden means the extension needs 2m foundations.

Then we decide to move utilities to the basement (washing machine etc). then we need ne central heating setup so 1st  room gets new cupboard with that in. then the sitting room (which opens out to the garden or now, the new kitchen-garden room/extension) needs re-doing (new power points every where which is good) - basement also needs some air circulation gear.

So new kitchen/extension has a small new bathroom in the corner, which is cool, and nice tiled floor which is neat, but that has underfloor heating which needs smart controllers. and  the rooms all need new smoke alarm systems. builder puts in a "mesh" net of stufff that runs off nest and so forth...
i  couldn't figure out at all how to actually turn off the underfloor heating - just put it in "holiday" mode, which says its off unless it detects a frost..obviously the smooke alarms have motion sensors  so you can find your way around at night (or smoke)....

fridge is smart too, apparently (if we want, when we're away, if ever again, and deciding to come back early (or late) can remote set everything back from holiday mode...)...

Now water pressure in top of house is too low, so need pumps in the attic....which trigger off water pressure, so if you leave a tap running, you can tell from the racket in the attic...

So then while doing sitting room, decide hey why not open up the old (early 19th century- apparently late georgian according to the chimney sweep) fireplace there, and close the one in an upstairs (1st floor) bedroom. oh, and why not just redecorate the 1st floor loo, and get some nice Portuguese tiles. oh, and lets just refit the 3rd floor bathroom too while we're about it. and the terrace above the kitchen. needs new tiles and parapet to be legal too...

Did I mention that meant all the plumbing and most the electrics in the house had to be redone (re-routed and replaced).

It does look nice, though...

A bit more than my annual salary, it bloody should:-)


Tuesday, May 05, 2020

Arguments for NHSX centralised approach to contact tracing.


1/ The NHSX Bluetooth works - it doesn't require the phone to be always on.

(incorrect assumptions by DP-3T critics claiming it does) and isn't blocked by Apple/Google - it won't kill your battery any more than using a BLE peripheral (e.g. airpods:) it is a  bit of a hack. and may place limits on detecting  some contacts.

2/ The "contact" proxy is pretty much based on what we did in fluphone a decade back so also fairly solid indication of proximity, but may need adaptation (as will all BLE based contact tracing apps whether centralised or decentralised). updates to the parameters in the algorithm can be computed in centralised approach somewhat more easily than decentralised (where you don't have the false -ve/+ve rate info).


3/  The rationale for centralising the data is several fold, which are nigh on impossible with decentralised apps:



a) You can update the algorithm in 2 based on measuring false positive/negative rates (there are other factors in deciding a contact is real too) - you can incorporate factors about the contactees in computing risk of infection, given the measured parameters of  the encounter.
b) The narrative script people use for self-reporting can be updated based on ROC that that achieves
c) You can detect hotspots in infection near real time (e.g. superspreader events).
d) Epidemiologists potentially get to run models on pseudonymised social contact graph < this is where you might baulk but they aren't publishing the data - it will stay put, and models be updated from that - if hackers gain access to this data (how?), then there's a risk some people's graph could be partially re-identified. there's no geo-loc data in the phone or uploaded data so probably rather limited threat - if data is deleted (as claimed) in 30 days, then that threat is also time limited...
4/ There's a human-on-the-loop in the self-diagnosis phase (drawn from pool of people that deal with manual contact tracing) (and obviously also in actual test if that's triggering a notification) they can decide there's no problem, which can revoke the notification to contacts (rather hard to do in decentralised apps). This limits cascades from false positives.
5/ Contacts of contacts (etc) can also in principle be notified (useful in small, fast local outbreaks/clusters - a real problem in this virus) - again, difficult to do in decentralised model meaningfully
I'd welcome hearing how the decentralised app folks will tackle some of these useful
challenges.
In common to all app based contact tracing is the acceleration over manual tracing, which has a marked impact on reducing the R0 of the pandemic. Contrary to claims that you need 60% of the population to be running the app, actually any number of people will help reduce contact times so reduce R0 - so it starts to be useful at low levels of deployment (as already pointed out, the epidemiologists find it useful at low levels already too since it lets them see SEIR parameters and spot any changes).
There's a lot of misinformation out there (nothing new about that:)

Ref white paper on NHSX app design.
Ref Limits on reduction of R0

Sunday, April 26, 2020

The legend of the book of the film of the record of the poem of the graffiti of the urban myth

"Which came first, the egg or the chicken?" is the perennially annoying question that consultant philosophers use to impress naive clients.

A much more serious question is why people hate the film  of the book, or  love the film, but  hate the book  it came from, or love the film, and hate the book  that came from it.

To solve this problem, I think we need to carry out a large scale analysis based in causal inference  (why not) .  Clearly we have the equivalent of the adaptive clinical trial or the series of unfortunate natural experiments to choose between. We can start with some obvious candidates.


  1. The Godfather
  2. Paddington
  3. The Princess Bride
  4. The Hobbit
  5. 2001 or The Sentinal
For each of these we need to look at all the possible features that could lead  one to prefer a book or a film (length, sentence structure, plot, character, year published, alphabetic position of author directors name, jokes, box office takings, time in best seller charts, influences, sequels, spinoffs, live action, cartoon, comic book, illustrated, etc etc) and build a bayesian model of how one moves from one state of mind (Hobbits are boring) to another (Smaug is cool), or from one opinion (why did no-one ever actually read the princess bride) to another (You keep using that word, etc etc ).

Two dominant theories to date are

  • The Ordering Theory
  • The Gap Theory


Then we will finally know the truth.

Wednesday, April 22, 2020

cat > /dev/kb


I'd like to bring up a very important topic for all my inky-fingered friends (and I am not
referring to my experiments with spilling Quink on the ebony fretboard to see if I can play faster).

The cats. come and sit. on the keyboard. in front of the screen. while you're trying to work.

How can we fix this? 

Well, here's my patented invention that I think is going to work.

You know how the keyboard layout was invented by Benjamin Franklin for President Theodore Roosevelt when he was digging the Panama Canal? It is an oft told tale - the problem was that all the typists producing  reports to send back to Washington DC had to type an inordinate number of lower case 'a's every time just to get the headed paper to look right. For this reason, they moved the keys for 'l', 'n', 'm' and 'p' as far away from the 'a' as they could get them. Back in those days, most people were one or two fingered typists so this slowed them down, so that the 'a' key stopped breaking, leading to incredible misunderstandings between the  rmy, nvy and rfrce ('o' was a lesser,but not insignificnt prblm).

So the new keyboards worked a treat until they started working with a French company who still used the old Aztec name Pznzmz Cxnxl, which led to the second new keyboard, which nous aimions tres biens ces jours. and so on and so forth.

As code breakers amongst you will remember, (or possible Sherlock Holmes stick insect fans) the problem is to do with the popularity of different letters f the alphabet in different tongues. Why the alphabet is in alphabetical order is an interesting question which I'll leave for later  (just noting for now that it isn't, for example, in Arabic, Hebrew, Greek and Cyril Smith's languages, the third letter is 'g', not 'c' - go figure how the Romans got that wrong along with really poor ways of counting). And of course, Scrabble scores - which are in the opposite order to the popularity of letters ( a bit like Nathaniel Hawthorne's novels).

So "how does this solve a problem like a cat?", I hear you ask, Maria.

Easy peasy. we place bigger springs under the unpopular letters and so when the cat sits on the nice warm laptop keyboard, instead of getting a gentle purr like vive from the fan, it gets prodded uncomfortable in random places.

This will also let us revert the keyboard layout to being alphabetic, since it will just be harder to depress the unpopular letters which will slow us down between popular ones.

Of course we could confuse the cat further (as if such a thing were possible or even desirable) by choosing springs from a French or dare I  even suggest, a Chinese (Mandarin, not Catonese (sic), of course) layout of spring constants. By Hooke or by Crooke, we will have to solve the problem that the Chinese layout would require at least 5 springs of different strengths to operate really successfully, but we believe that yhe market for this in china will be as big as that for Dragon Nets.

I will be inviting investors to my alpha-beta-gamma product launches shortly, meanwhile I leave you with the experimental result that  you may wish to try as well, in these distracted days. You can teach your cat a foreign language easily. I have ours completely versed in French - when I say va't en or viens ici, she behaves in exacfly the same way as when I say "get the 'f off that keyboard" or "where are you didums". This does not work with dogs. In fact I know several dogs in the Dordogne that response to "Get off my leg fido" in exactly the same way as if you offer them a biscuit.

Science is a marvellous thing when used carefully.Electromagnets more so - in the new version (delta-key) of the boards above, we replace the springs by electromagnets and now can use this to train humans to type faster, and untrain cats to sit on the keys. Gnu Emacs key bindings will be available shortly.

References

Keyboards:
qwerty or azerty

Frequentists:
code breakers and scrabble

Dvorak:
chording

Medication:
While waiting for the coffee to brew,

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misery me, there is a floccipaucinihilipilification (*) of chronsynclastic infundibuli in these parts and I must therefore refer you to frank zappa instead, and go home