## moral [dis]order

Posted in Kids, Travel with tags , , , , , , on October 3, 2015 by xi'an

“For example, a religiously affiliated college that receives federal grants could fire a professor simply for being gay and still receive those grants. Or federal workers could refuse to process the tax returns of same-sex couples simply because of bigotry against their marriages. It doesn’t stop there. As critics of the bill quickly pointed out, the measure’s broad language — which also protects those who believe that “sexual relations are properly reserved to” heterosexual marriages alone — would permit discrimination against anyone who has sexual relations outside such a marriage. That would appear to include women who have children outside of marriage, a class generally protected by federal law.” The New York Time

An excerpt from this week New York Time Sunday Review editorial about what it qualifies as “a nasty bit of business congressional Republicans call the First Amendment Defense Act.” A bill which first line states to be intended to “prevent discriminatory treatment of any person on the basis of views held with respect to marriage” and which in essence would allow for discriminatory treatment of homosexual and unmarried couples not to be prosecuted. A fine example of Newspeak if any! (Maybe they could also borrow Orwell‘s notion of a Ministry of Love.) Another excerpt of the bill that similarly competes for Newspeak of the Year:

(5) Laws that protect the free exercise of religious beliefs and moral convictions about marriage will encourage private citizens and institutions to demonstrate tolerance for those beliefs and convictions and therefore contribute to a more respectful, diverse, and peaceful society.

This reminded me of a story I was recently told me about a friend of a friend who is currently employed by a Catholic school in Australia and is afraid of being fired if found being pregnant outside of marriage. Which kind of “freedom” is to be defended in such “tolerant” behaviours?!

## melting hot!

Posted in Kids, pictures, Travel with tags , , , , on September 29, 2015 by xi'an

Despite majoring in her Physics class last year, my daughter forgot that microwaves are not very friendly to metal objects. Like this coffee tumbler I had brought back from Seattle, albeit not from Starbucks. The plastic part melted really well, even though the microwave oven resisted the experiment… And the coffee inside as well.

## Le Monde puzzle [#929]

Posted in Books, Kids, R with tags , on September 29, 2015 by xi'an

A combinatorics Le Monde mathematical puzzle:

In the set {1,…,12}, numbers adjacent to i are called friends of i. How many distinct subsets of size 5 can be chosen under the constraint that each number in the subset has at least a friend with him?

In a brute force approach, I tried a quintuple loop to check all possible cases:

case=0
for (a in 1:(12-4))
for (b in (a+1):(12-3))
for (c in (b+1):(12-2))
for (d in (c+1):(12-1))
for (e in (d+1):12)
case=case+((b-a<2)&(min(c-b,d-c)<2)
&(min(d-c,e-d)<2)&(e-d<2))


which returns 64 possible cases. Note that the second and last loop are useless since b=a+1 and e=d+1, necessarily. And c is either (b+1) or (d-1), which means 2 choices for c, except when e=a+4. This all adds up to

$8 + 2\sum_{a=1}^7\sum_{e=a+5}^{12} = 8+2.7.8-2.7.8/2=8.8=64$

A related R question: is there a generic way of programming a sequence of embedded loops like the one above without listing all of the loops one by one?

## Salman Rushdie at the Banff Centre

Posted in Books, Kids, Mountains, pictures, Travel with tags , , , , , , , , , on September 28, 2015 by xi'an

By a great coincidence, I happened to be in Banff the same weekend as Salman Rushdie was giving a talk at the Banff Centre on his latest book! And got the news early enough to book a seat. The amphitheatre was unsurprisingly full and Salman Rushdie was interviewed by Eleanor Wachtel, first about the book and what led to its creation, especially the influence of his parents, and then second about his life and career, with an obvious focus on Khomeini’s fatwa. (The whole interview is podcasted on CBC.) Rushdie was witty and funny, even about the darkest moments, and discussed how in his youth no one would have imagined that religion would become such a central issue, defining and reducing people rather than being a part of them that would need no discussion. And how his family was de facto atheist, if not in words. The interview spent too little time on Rusdhie’s stand on freedom of expression, although he briefly spoke about the growing threats to this freedom, including those made in the name of religious freedom. (As we were reminded yesterday by the Warwick student union decision to bar Maryam Namazie from speaking on campus.) The experience was quite a treat, adding to the many bonuses of spending this weekend in Banff. Although I must admit I was fighting jetlag that late at night and hence must have dozed at points… (As an aside, I was rather surprised to see no security or police around the Banff Centre theatre, but of course this does not mean there was none. And this is Banff, not New York City or London.)

## where on [Middle] Earth can a book be banned for moral arguments?

Posted in Books, Kids, Mountains, Travel with tags , , , , on September 27, 2015 by xi'an

Well, the clue in the title should be obvious enough: A censorship board in New Zealand, the Film and Literature Board of Review, has just banned Ted Dawes’ “Into the River” from being sold or distributed or even exhibited. Following complaints orchestrated by Family First, a conservative organisation… The ban is actually temporary, until a committee reaches a decision about the classification of the book. The most surprising aspect of this story—besides the existence of a censoring institution in a democratic country in 2015!— is that the ban applies to everyone, including adult readers, and that all libraries had to take the book out of their shelves. Which is also fairly ridiculous in the era of e-books…

## mixtures, Heremite polynomials, and ideals

Posted in Books, Kids, Statistics, University life with tags , , , , on September 24, 2015 by xi'an

A 3 page note that got arXived today is [University of Colorado?!] Andrew Clark’s “Expanding the Computation of Mixture Models by the use of Hermite Polynomials and Ideals“. With a typo on Hermite‘s name in the pdf title. The whole point of the note is to demonstrate that mixtures of different types of distributions (like t and Gaussian) are manageable.  A truly stupendous result… As if no one had ever mixed different distributions before.

“Using Hermite polynomials and computing ideals allows the investigator to mix distributions from distinct families.”

The second point of the paper is to derive the mixture weights from an algebraic equation based on the Hermite polynomials of the components, which implies that the components and the mixture distribution itself are already known. Which thus does not seem particularly relevant for mixture estimation…

## running out of explanations

Posted in Books, Kids, Statistics with tags , , , , , on September 23, 2015 by xi'an

A few days ago, I answered a self-study question on Cross Validated about the convergence in probability of 1/X given the convergence in probability of X to a. Until I ran out of explanations… I did not see how to detail any further the connection between both properties! The reader (OP) started from a resolution of the corresponding exercise in Casella and Berger’s Statistical Inference and could not follow the steps, some of which were incorrect. But my attempts at making him uncover the necessary steps failed, presumably because he was sticking to this earlier resolution rather than starting from the definition of convergence in probability. And he could not get over the equality

$\mathbb{P}(|a/X_{i} - 1| < \epsilon)=\mathbb{P}\left(a-{{a\epsilon}\over{1 + \epsilon}} < X_{i} < a + {{a\epsilon}\over{1 - \epsilon}}\right)$

which is the central reason why one convergence transfers to the other… I know I know nothing, and even less about pedagogy, but it is (just so mildly!) frustrating to hit a wall beyond which no further explanation can help! Feel free to propose an alternative resolution.

Update: A few days later, readers of Cross Validated pointed out that the question had been answered by whuber in a magisterial way. But I wonder if my original reader appreciated this resolution, since he did not pursue the issue.