- [University Rankings]
- From observation at the local lake,
about half of the birds are coots,
30% are ducks, and
20% are swans.
Most ducks and swans, say 90%, have been seen to waddle.
No coot has been seen to waddle (but maybe one could),
pr(B waddles|B is a coot) = 0.1, say.
Most ducks, say 90%, have been heard to quack.
No coot has been heard quacking,
pr(B quacks |B is a coot) = 0.1, say.
Similarly for swans.
Someone reports that a certain bird, X, was observed to waddle and to quack.
What species, S, is X?
pr(B is a S|B waddles & B quacks)
∝ pr(B is a S) . pr(B waddles|B is a S)
. pr(B quacks|B is a S),†
pr(X is a coot) ∝ 0.5 × 0.1 × 0.1 = 0.005,
pr(X is a duck) ∝ 0.3 × 0.9 × 0.9 = 0.243,
pr(X is a swan) ∝ 0.2 × 0.9 × 0.1 = 0.018,
total 0.005 + 0.243 + 0.018 = 0.266.
pr(X is a duck | X waddles, X quacks) = 0.243 / 0.266 = 0.91
-- if it walks like a duck and talks like a duck it is
(probably) a duck, according to naive Bayes.
(Bayes because of the use of
naive because waddling and quacking are assumed to be independent.)
- The Federal Court of .au ruled [FCA 65]
against 'Cancer Voices [.au],' and
for "US-based company Myriad Genetics and
Melbourne-based Genetic Technologies, over the
patent on a breast and ovarian cancer gene known as BRCA1 ...
Justice John Nicholas ruled that the gene could be patented, as it
had been isolated completely separately from the human body.",
A pity, I think.
- The International Table Soccer Federation
(i.e., foosball) has
and videos of past championships
- Have finally disentangled the mathematics in the
various meandering explanations of the
von Mises - Fisher
probability distribution on directions in RD
and of MML-ing it.
- In some cultures sons are valued more than daughters and the
male:female sex ratio at birth is
much higher than one (ultra-sound, abortion, ...);
the ratio is reported to be
as high as 1.19:1 in China (WDB).
Fisher (1930) showed that natural selection drives
the ratio to 1:1 :
Every child has one mother and one father.
If there is an excess of males, a male has a lower chance of having
children than a female. (And v.v. if there is an excess of females.)
So, someone having a daughter in such a culture is more likely
to have grandchildren than someone having a son.
A tendency to have daughters is
being selected for. Just give nature time.
selection drives the ratio at reproductive age to 1:1.
The argument does not hold for all species, e.g.,
where females have multiple young, over time, after a single mating, say.
Search for [sex ratio biology] in
- The alien computer design in
A for Andromeda
(1961) still looks more than a match for a human
in terms of neuron numbers, but not in synapses;
there again, there's the matter of speed.
stable marriage problem
featured in the 2012 Nobel prize for Economics.
is a documentary.
- The good old
Iterated Prisoners' Dilemma (IPD).
- Enumerating all sequences of n pairs of
is equivalent to generating rooted, ordered, k-ary trees.
algorithm finds Eigen things of a real, symmetric matrix.
- I really wish I had invented the
transform, in which case it would not be known as the BWT.