Archive for November, 2010

November 28, 2010

Il 25 Novembre 2010, a 17 anni, muore la Mimma. Il paradiso dei gatti è un grande prato con siepi fresche sotto cui acciambellarsi e grandi alberi soleggiati su cui farsi le unghie.

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Semantophoretic, episemantic, asemantic.

November 24, 2010

« Of all natural systems, living matter is the one which, in the face of great transformations, preserves inscribed in its organization the largest amount of its own past history. Using Hegel’s expression, we may say that there is no other system that is better aufgehoben (constantly abolished and simultaneously preserved). »

« One may classify molecules that occur in living matter into three categories, designated by new terms, according to the degree to which the specific information contained in an organism is reflected in them: (1) semantophoretic molecules or semantides — molecules that carry the information of the genes or a transcript thereof. The genes themselves are the primary semantides (linear “sense-carrying” units). Messenger -RNA molecules are secondary semantides. Polypeptides, at least most of them, are tertiary semantides. (2) Episemantic molecules — molecules that are synthesized under the control of tertiary semantides. All molecules built by enzymes in the absence of a template are in this class. They are called episemantic because, although they do not express extensively the information containe in the semantides, they are a product of this information. (3) Asemantic molecules — molecules that are not produced by the organism and therefore do not express, either directly or indirectly (except by their presence, to the extent that this presence reveals a specific mechanism of absorption), any of the information that this organism contains. »

~ “Molecules as documents of evolutionary history”. E. Zuckerkandl, L. Pauling. 1965.

Identity of indiscernibles

November 23, 2010

d(a,b)=0 iff a=b is also called “identity of indiscernibles”.

November 21, 2010

Compressing before encrypting or encrypting before compressing?

Proving NP-Completeness

November 20, 2010

« To prove NP completeness: (1) Ask if the problem can be discretized, e.g. ability to break analog audio into discreet samples. If no, may be NP complete. (2) Is there a finite way to solve this (even if looping/recursion involved)? Can the problem always be solved this way? E.g. using recursive calls to find Fibonacci numbers at nth place. If no, NP complete (though further analysis may make this into sub-function of larger algorithm). (3) Is the solution always the same no matter what tweaks are made? If no, the problem has many routes to solve it. E.g. FFT analysis since FFTs can vary in accuracy of frequency analysis, allowing some speed. » ~ From an undergraduate midterm exam.

November 20, 2010

Say you have one string of alphabetic characters, and say you have another, guaranteed smaller string of alphabetic characters. Algorithmically speaking, what’s the fastest way to find out if all the characters in the smaller string are in the larger string?

What if – given that we have a limited range of possible characters – I assigned each character of the alphabet to a prime number starting with 2 and going up from there. So A would be 2, and B would be 3, and C would be 5, etc. And then I went through the first string and ‘multiplied’ each character’s prime number together. You’d end up with some big number right? And then – what if I iterated through the 2nd string and ‘divided’ by every character in there. If any division gave a remainder – you knew you didn’t have a match. If there was no remainders through the whole process, you knew you had a subset.

November 19, 2010

« When king Ferdinand visited the conservative university of Cervera, the rector proudly reassured the monarch with the words: “Far be from us, Sire, the dangerous novelty of thinking”. » ~ “On the cruelty of teaching computing science”, E.W. Dijkstra

Nostalgia

November 18, 2010

Anche tu sei l’amore.

November 18, 2010

Anche tu sei l’amore.
Sei di sangue e di terra
come gli altri. Cammini
come chi non si stacca
dalla porta di casa.
Guardi come chi attende
e non vede. Sei terra
che dolora e che tace.
Hai sussulti e stanchezze,
hai parole – cammini
in attesa. L’amore
è il tuo sangue – non altro.

 

-C.P.-

 

Cinnamon brooms

November 14, 2010

The cinnamon brooms handcrafted in Cleveland, Georgia, USA, are just amazing.