| Andrew Cooke | Contents | RSS | Twitter | Previous


Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

© 2006-2015 Andrew Cooke (site) / post authors (content).

Not The Onion: Google Fireside Chat w Kissinger

From: andrew cooke <andrew@...>

Date: Fri, 24 Apr 2015 17:17:15 -0300


> In recent years, many of us have gone from reading books to quickly
> digesting lots of information online through short headlines. But when you
> learn things in fragments, you lose nuance and context

...like chatting with war criminals?



Permalink | Comment on this post

Previous Entries

For comments, see relevant pages (permalinks).

Bicycle Wheels, Inertia, and Energy

From: andrew cooke <andrew@...>

Date: Sun, 19 Apr 2015 17:44:45 -0300


It's common to hear that larger bicycle wheels accelerate more slowly because they have a larger moment of inertia. But a thread on Reddit raised interesting questions that pushed me to think more carefully about the physics involved.

Physical Model

First, we need a model for a wheel. I will ignore the hub, and consider just two components - spokes and "rim and tyre together" (for simplicity I'll sometimes refer to the latter as just "rim" below, but the tyre is obviously important too).

(I'm excluding disks because I am not sure how they are made. I may return to them later).

I'm assuming that spokes are of length \(r\), while the rim and tyre are of length \(2\pi r\). That is an approximation - the spokes are shorter, and the rim is slightly shorter than the tyre, and of finite depth. But it's likely good enough.

Masses and Moments of Inertia

To get masses I'll use linear density for all the spokes (summed). In other words, \(M_S = r \, \rho_S\). Similarly, for the rim, \(M_R = 2 \pi \, r \, \rho_R\). So the total mass \(M = r \, (2 \pi \rho_R + \rho_S)\)

The moment of inertia of the rim, \(I_R\), about the axle is simple, just \(M_R r^2\) or \(2 \pi r^3 \rho_R\).

The moment of inertia of the spokes is a little more complex because they are not a disk (the effective density decreases with radius). So let's go back to basics:

\[I_S = \int_0^r x^2 \rho_S \, dx = r^3 \rho_S \, / \, 3\]

So the total moment of inertia of the wheel is \(I = r^3 (2 \pi \rho_R + \rho_S / 3)\).


To accelerate a bicycle to velocity \(v\) we need to expend energy in both accelerating the centre of mass and in rotating the wheel. When the bike is moving with velocity \(v\) the wheel rotates with angular velocity \(\dot\theta = v / r\). The total energy required is

\[E = \frac{1}{2} (M v^2 + I \dot{\theta}^2) = \frac{1}{2} v^2 \left[r (2 \pi \rho_R + \rho_S) + r (2 \pi \rho_R + \rho_S/3)\right] = 2\,rv^2(\pi \rho_R + \rho_S / 3)\]

It's interesting to express this as a ratio relative to the energy from the centre of mass alone. This gives the factor of "extra work" because the wheel rotates:

\[X = \frac{2\,rv^2(\pi \rho_R + \rho_S / 3)}{rv^2 \, (2 \pi \rho_R + \rho_S) / 2} = \frac{4\pi \rho_R + 4\rho_S / 3}{2 \pi \rho_R + \rho_S}\]


First, pretty clearly, \(X>1\). In other words, as is commonly known, rotating mass hurts. It's close to twice as "bad" in terms of the total energy required to reach a particular speed.

Second, \(E\) increases with \(r\). That means that larger wheels mean you need to do more work. But how much more?

There are two ways to look at this. One way is to note that because \(X > 1\), a larger wheel is worse than you would expect from the weight alone. The "effective mass" is almost twice as bad. But the other way is to note that, perhaps counter-intuitively, that relationship is only linear. You might expect increasing wheel size to hit you "quadratically" - more than you'd expect from the effective mass alone. But it doesn't. And one way to explain this is given in the Reddit thread I linked to earlier - for a given speed over the ground, a larger wheel rotates more slowly.



Another Tax Fraud

From: andrew cooke <andrew@...>

Date: Sun, 19 Apr 2015 15:52:51 -0300


  This is a loose translation of an article in La Tercera, 2015-04-19.
  The online version can be seen at 

  This translation is unofficial, amateur, and made mainly to help improve my
  Spanish.  Please do not rely on this for any important detail.


The Sophisticated $8,000m (US $13m) Tax Fraud

* The accused used a complex network of companies to avoid paying taxes for 6

* Fraudulent tax invoices were exchanged between companies.

By Felipe Diaz and Victor Rivera [original byline]

At the end of Q3 2014, before false tax invoicing was a common topic of
conversation, the Tax Office (SII) detected a series of irregular returns from
a group of investors who planned to defraud the State of $8,638,098,553
between 2005 and 2011.

So started an investigation of one of the country's largest tax evasions, both
by total amount and number of people involved.

On October 21 2014 the SII lodged a complaint with an investigating Judge
[7th Juzgada de Garantia de Santiago] against 5 people for tax evasion [delito
tributario sancionado en el articulo 97 no 4] - the submission of maliciously
incomplete and incorrect tax declarations.

According to the SII investigation the accused had "created fictitious
companies whose only function was to increase IVA [VAT / Purchase Tax]
credited to other companies owned by the same group, decreasing the taxable
income declared to the authorities" [I'm unsure on the exact details].

Evidence was provided to the Public Prosecutor [Fiscalia Centro Norte] and
Police (Financial Crimes Division) [Brigada Investigadora de Delitos
Economicos Metropolitana (Bridec) de la PDI].

Modus Operandi

According to the investigation, the first network of companies was constructed
between 2005 and 2008 by the accused Luis Mardones Sanches, together with
Fernando Nanjari Alvarez, acting as legal advisor, and Fernando Kiblisky
Budnik, as financier.  They created 6 companies (staffing agencies): Servicios
de Personal Urbe DA; Servicios Integrales de Personal SA; Productora Nacional
de Servicios SA; Gamma Servicios de Personal SA; Global Work SA; and Delta SA.

The aim, according to the complaint, was to "provide false invoices to
companies Delta SA and, finally, Cicorp SA (administered by the accused Miguel
Sepulveda Eljatib and his legal representative (and company lawyer) Mario
Cartes Eljatib)."

Similarly, "Cicorp SA, in turn, provided false invoices to Telecommunicaciones
Siglo XXI SA, Intercity Service, Nuble Ingenieria SA, Constructora Perez y
Gomez SA, who all charged for supposed computational services, for plans and
three dimensional models.  These companies were controlled by the accused
Miguel Sepulveda Eljatib and Mario Cartes Eljatib."

During that period, according to SII estimates, the fraud amounted to

Between 2009 and 2011 the formula was repeated.  Some companies were
continued, and Bristol SA, Agency SA, and Laborum SA were added, as staffing
agencies, providing services to Delta SA and Milenium SA, which in turn
invoiced for non-existent services to Efco Servicios Generales SA.  The amount
involved over this period comes to $2,962,941,208.

The complaint ends with "all the details above, taken together, show
irregularities involving all the companies, with the aim of avoiding tax on
sales and services, using false invoices on non-existent commercial
operations [again, not sure I have this exact]."


La Tercera tried to locate all the involved, succeeding only in contacting the
lawyer of Cicorp SA, Mario Cartes.

Via email he said that "I am not the legal representative, nor a member or an
investor, in any of the companies mentioned in the complaint.  I also have no
relationship with the other people listed, except Miguel Sepulveda, who is a
relation, and I have been lawyer for him personally, and for his company,
Cicorp SA."  He added that "with respect to the objections made against
providers to Cicorp SA, I have cooperated completely since 2009, when I
delivered to the SII all the accounting and tax details they requested, and so
I expect that when the investigation is complete the situation will be


Google's Borg

From: andrew cooke <andrew@...>

Date: Sun, 19 Apr 2015 14:02:36 -0300

A paper I should read some time




Spanish Accents For Idiots

From: andrew cooke <andrew@...>

Date: Thu, 16 Apr 2015 08:18:30 -0300

My homework.



PS I am taking spanish lessons from a phonologist (wife of a friend) and it's
really helping.


Aluminium Cans

From: andrew cooke <andrew@...>

Date: Wed, 15 Apr 2015 20:35:08 -0300


How the pull-tab works, at the end, is particularly interesting.



Advice on Spray Painting

From: andrew cooke <andrew@...>

Date: Wed, 15 Apr 2015 18:14:50 -0300




Female View of Online Chat From a Male

From: andrew cooke <andrew@...>

Date: Tue, 14 Apr 2015 13:28:40 -0300




UX Reading List

From: andrew cooke <andrew@...>

Date: Mon, 13 Apr 2015 06:35:19 -0300

No idea how complete it is, but a couple of interesting looking titles I would
like to read at some point.




S4 Subgroups - Geometric Interpretation

From: andrew cooke <andrew@...>

Date: Sun, 12 Apr 2015 20:48:24 -0300

Interesting discussion / example -



Fucking Email

From: andrew cooke <andrew@...>

Date: Sat, 11 Apr 2015 19:37:44 -0300

I spent a day translating an article on SQM from Spanish to English.  The
email contained, as an aid to formatting, a line with a single dot, at the

People as old as me may remember that a single dot is also how you terminate a
message using the primordial Unix mail command.  And it seems that somewhere,
in the layers of abstraction that current email is built from, that is still
interpreted as the end of the message.

So my entire email was discarded, except for the header.

Fucking email sucks in so many ways.  Still, if I have "From" at the start of
a line, it is prefixed by >, somewhere, in some kind of hack to avoid it being
interpreted as the sender.  And, of course, no authentication.  No

Sigh.  I may try again tomorrow; perhaps second time round it will be quicker.



The SQM Affair For Idiots

From: andrew cooke <andrew@...>

Date: Sat, 11 Apr 2015 17:55:20 -0300


  This is a loose translation of 
  by Matias Godoy Mercado.

  I cannot guarantee the truth of what is written below for two reasons.
  First, my Spanish is imperfect.  I am particularly unsure of technical terms
  (eg "impuesto de primera categoria").  Second, I don't have the general
  knowledge of Chilean politics necessary to check the details given (I am
  translating partly to learn about these things myself).  So please use the
  original (linked above) as reference.

  See also
  * The Penta Affair For Idiots http://acooke.org/cute/ThePentaAf0.html

  I generally translate the names of government institutions and common
  Chilean details like Boletas:
  * La Fiscalia - Prosecutions Office (CPS/DPP in UK, Attorney General in USA)
  * Fiscal - Public Prosecutor
  * SII (Servicio Impuestos Internos) - Tax Office
  * Boletas De Honorarios - Tax Invoices (emitted by the person being paid for
    some professional service)
  * SVS (Superintendencia de Valores y Seguros) - Securities Commission (FSA
    in UK)
  * AFP (Administradoras de Fondos de Pensiones) - Pension Funds
  * La Moneda - Presidential Palace
  * Fisco - Treasury

  I have decided not to translate names of companies and political parties,
  so here is a quick glossary of the main parties (right to left):
  * UDI - Union Democrata Independiente / Independent Democratic Union
  * RN - Renovacion Nacional / National Renewal
  * PRI - Partido Regional Independiente / Regional Independents
  * PDC - Partido Democrata Cristiana / Christian Democrats
  * PPD - Partido Por La Democracia / Party For Democracy
  * PS - Partido Socialista / Socialist Party
  * PC - Partido Comunista / Communist Party
  where UDI/RN are members of Alianza Por Chile (right), and the others
  members of the Nueva Mayoria (prev La Concertacion) (centre+left).
  * RUT - personal ID number (SSN in USA)
  * CORE - regional assemblies
  * Senado (upper chamber of Parliament) is composed of Senators
  * Camera de Diputados (lower chamber) is composed of Delegates

  I have added comments in [square brackets].  Comments (in parentheses)
  are present in the original.

  Finally, my thanks to Matias, who I have been unable to contact (if anyone
  knows his email, please tell me at andrew @ acooke.org)


In this column I [ie Matias] will give the background to the SQM (or
Soquimich) case, to date [the column was written on 2015-03-16 and there have
been developments since - see comment below].  Although, to be exact, the "SQM
case" is not yet a "case".  Give this, some people are calling it an "angle"
on the Penta Affair.  But, given the current data (scarce but meaty), I feel
more comfortable calling it a "case", even though it is not, yet, for the Tax

In the first section I will talk about Soquimich, the Chilean company.  In the
second section, we'll take a brief look at the Cascadas Affair, which involved
this and related companies, for context about who we are discussing.  In the
third, I will discuss the evidence for a careful and detailed examination of
this company, given the apparent irregular financing of political campaigns,
and fiscal fraud.  In the fourth part I will address the strange conflict
between the Prosecutions and Tax Offices (SII and Fiscalia), in this case.
[There was also a fifth section, which I have not translated, which was mainly
a call to get people to tweet in the hope of changing the policy of the SII.
Instead, I've added a note explaining how things developed.]

Sociedad Quimica Y Minera De Chile (Soquimich or SQM)

The Sociedad Quimica Y Minera De Chile (SQM) is a private mining company
dedicated to the extraction, processing and marketing of mineral products;
mainly iodine, potassium and lithium.  It was created in 1968 as a mixed
public / private enterprise, like many of the large Chilean companies.  In
1971 it passed into the control Corporacion De Fomento A La Produccion
(CORFO), ie the Chilean State.  Then, during the 80s, it was privatised.
[Some historical context: Allende was elected in 1970; the coup lasted from
1973 to 1990].  This company won the rights to develop lithium mining.
[Beating 5 other companies in a controversial contest; the then Minister of
Mining was the brother of the SQM Executive Vice President -

From December 2012 Sociedad de Inversiones Pampa Calichera S.A., Inversiones
Global Mining (Chile) Ltda, and Potasios de Chile S.A. (together, Grupo Pampa)
control 31.97% of the shares in SQM.  The head of SQM is Sr. Julio Ponce
Lerou, Forestry Engineer from U of Chile, ex son-in-law of Gen. Augusto
Pinochet Ugarte, who is currently President of the Board of Directors of SQM
SA, Norte Grande SA, Oro Blanco SA and Sociedad de Inversiones Pampa Calichera

Julio Ponce And The Cascadas Affair

In September 2013, after questions were raised by Moneda Asset and Chilean
Pension Funds (AFP) about the financial state of SQM, the Securities Commission
(SVS) brought charges against Julio Ponce Lerou for his responsibility in
various synchronised market trades between 2009 and 2011, that led to the
assumption of price rigging in SQM shares, leading to losses on the part of
the Pension Funds and Moneda Asset.

Julio Ponce remains in control of SQM despite the scheme called "cascada"
[waterfall].  How did it work?  We will return to Snoopy.  Suppose that Snoopy
is owner of 51% of the shares in a company called Gold.  The company Gold, in
turn, owns 51% of the shares in a company called Silver.  So Snoopy controls
both companies: Gold directly, and Silver though Gold.

Let's complicate things a little.  Snoopy owns 51% of the actions in a company
called Gold.  But now Gold only owns 25 of the shares in Silver.  However,
Snoopy has another channel.  As well as shares in Gold, Snoopy has 51% of the
shares in a company called Copper.  And Copper owns 26% of the shares in
Silver.  In this way, Snoopy controls Gold and Copper directly, and Silver
through two different channels.  The name "waterfall" comes from how the
control of the companies flows from top to bottom, like w a waterfall.

Julio Ponce has control of SQM through two "cascadas".  Julio Ponce controls a
company called Norte Grande, which controls Oro Blanco, which controls Pampa
Calichera, which, finally, controls 23% of the shares in SQM.  In addition,
Norte Grande controls Nitratos de Chile, which controls Potasios de Chile,
which also has shares in SQM: 7%.  So in total Ponce controls 30% of the
shares in SQM, indirectly.

What Ponce did was as follows.  He sold low and bought high.  What was he
dealing in?  Shares of SQM, Pampa Calichera, and others.  Ponce, via some
company in the "cascada", sold shares of another company in the "cascada", at
a lower than market price, to a third company, X.  This company X then resold
the shares back to a company in the "cascada", at a price higher than market
price.  The result?  To artificially change the value of shares in the
transactions.  These operations were made with 5 minutes delay.  That is,
Ponce recovered the shares he had sold 5 minutes earlier at a higher price.
He did this repeatedly.  In 5 minutes Ponce was able to manipulate his share
price, thanks to the intermediary.  In 5 minutes Ponce changed something that
cost $50 into something that cost $70.

If it's not clear, here's my final attempt.  Returning to Snoopy.  Snoopy
controls Gold, which has shares in Silver.  And Snoopy controls Copper, which
also has shares in Copper.  Suppose that Snoopy calls his friend Charlie, who
controls the company Peanuts.  Snoopy says "buy my shares in Silver, I'll sell
you them cheap, but you've got to sell them back to me at a higher price
afterwards."  Charlie asks "what's in it for me?"  Snoopy replies "the
difference in price."  Charlie accepts.  Charlie, through Peanuts, buys a
share in Plata at $50 from Gold.  The company Gold, and all its shareholder
lose by selling the share so cheaply.  Then Peanuts sells the share in Plata
to Copper, at $70.  Peanuts earns $20.  Snoopy continues to control Silver and
the shares have changed in value: what was worth $50 is now worth $70.  Gold
lost.  Copper lost too, because they paid $70 for something worth less.

The Securities Commission (SVS) fined 8 executives and a stockbroker,
including Julio Ponce and Leonardo Vial, ex President of the Board of
LarrainVial SA and majority shareholder in Blanco y Negro SA (Colo Colo) [one
of the big Chilean football clubs].  The fines reached USD $164m, one of the
highest fines from the Commission in decades.

SQM And Politics: The New Penta

Months passed and the Cascadas Affair faded from the press.  The 2013
presidential and parliamentary elections were in the spotlight, and attention
was focused on the fight between the 9 presidential candidates, the right
wing primaries, the fuzz leadership of Michelle Bachelet, and others.  The
government changed; Michelle Bachelet became President of the Republic; taw
reform; education reform; etc.  SQM could relax.  It was only the eye of the
hurricane, but it seemed like the case was closed.  The fines seemed kinder
than the public criticism.  But, as the priest said, some sins still needed to
be forgiven.

The press jumped on the Penta Affair.  Which you already understand perfectly.
If not, I suggest you read
[translated at http://www.acooke.org/cute/ThePentaAf0.html].  One of the
critical points of the Penta affair was the evidence of a possible crime of
bribery and asset laundering by the ex Sub-secretary of Mining, Pablo Wagner.
This, thanks to the testimony of Hugo Bravo, ex Managing Director of Empresas
Penta.  The work of the Prosecutions Office intensified, hoping to shed
further light on this particular angle.  And so they arrived at Carolina de la
Cerda, sister in law of the Sub-secretary.

Carolina de la Cerda testified to having issued Tax Invoices for Pablo Wagner.
She wrote the invoices to avoid Wagner appearing to be offering services, as
he was already Sub-secretary of Mining.  The Prosecutions Office was going
after Empresas Penta.  But Carolina de la Cerda gave them something else:
Soquimich.  Carolina de la Cerda testified: "(Wagner) gave me a phone number to
call when the money arrived, to cash three cheques for people and amounts
specified, the person, whose name I can't remember, gave me the names Cristina
Bitar, Ernesto Silva Bafalluy and Lorena Espinoza.  I wrote the invoice for
the company Soquimich for 'financial services'."  [The original Spanish is
garbled, to me, and my translation is even worse here than elsewhere.]  With
this information it was clear that Empresas Penta was not the only company
irregularly financing political campaigns through false invoicing.

With this information the Tax Office (SII) took action against Pablo Wagner
and Carolina de la Cerda.  At first, SII asked for all the accounting data for
financial years 2009 to 2014.  Then, later, and unusually, clarified their
position to the Prosecutions Service and limited themselves to July 2009.  On
January 16 the Prosecutions Service took information from the offices of SQM,
who gave them the accounts voluntarily.

The Public Prosecutor Carlos Gajardo studied the accounting.  He found 19
suspect RUTs.  El Mostrador gained access to a note sent from SQM to the SII
concerning 240 RUTs that invoiced the company in 2010
The newspaper / site claims that these have connecting with 39 Chilean

Politicians Of Nueva Mayoria

Fulvio Rossi (PS Senator), Marcelo Rozas (PDC, ex Ambassador, Czech Republic),
Raul Castro (PDC, CORE Arica y Parinacota), Roberto Leon Araya (son of Delegate
PDC Roberto Leon), Hernan Rivera Letelier (PS, writer, ex candidate Delegate).

Politicians of Alianza Por Chile

Presidential campaign collaborators for Sebastian Pinera (RN, ex President),
advisors for Lavin Infante (UDI, ex Minister), a son of Pablo Longueira (UDI,
ex Minister), advisors for Pablo Zalaquett (UDI, ex Mayor), advisor to Jaime
Orpis (UDI Senator), advisor to Juan Antonio Coloma (UDI Senator), Gustavo
Alessandri (UDI, CORE Puente Alto), y Jorge Brito (PRI CORE Region del

The Division Between The Prosecutions Office And The Tax Office

The Prosecutions Office wanted to continue investigating SQM, extending the
accounting data to the period between 2009 and 2014.  But to obtain those
documents then needed the SII to press charges for tax evasion.  But the SII
has not taken action against SQM.  The newspaper La Tercera published a lead
article on Sunday 15 December, under the heading "The Escape Hatch That
Worries The Prosecutors".  They lead with: "While the Prosecutions Office
looks to seize all the accounting of SQM, the SII flexed its muscles and
opened a hatch allowing the political angle in the Penta case to hide far from
court.  The decision was welcomed by the entire political spectrum, starting
from the Presidential Palace."  [Translation not so good here.  Flowery,
mixed-metaphors in the paper.]

SQM has not provided the information requested by the Prosecutors.  The SII is
hoping for compensation from SQL to the Treasury, avoiding an investigation.
The Prosecutions Office can't believe it.  Neither can I.

  [The original article was written on 2015-03-16.  Since then things have
  changed.  For example, from

  "At first light, today, the Tax Office will deliver to the Prosecutions
  Office accounting material for the company SQM corresponding to the period
  from 2009 to 2014, which the Prosecutor requested as part of the
  investigations for irregular financing of political campaigns"]