Antonio E. Porreca 🐳
@aeporreca.org
Maître de conférences (lecturer) at https://univ-amu.fr & researcher at https://lis-lab.fr 🐗🇫🇷 • Natural computing, discrete dynamical systems & complexity • Down with generative AI • I like (human) languages • This is a pandemic, y’all 😷 • aeporreca.org
Chris Okasaki on teaching data structures. 🙏
![A common failing in the way we teach data structures and algorithms is presenting finished products rather than guiding students through the algorithmic design steps necessary to reach that product. For example, presentations of red-black trees (including our own!) commonly conjure the red-black invariants out of thin air. As a second example, consider leftist heaps [6]. Leftist heaps are simple to understand, simple to code, and simple to analyze, but students typically regard the leftist height invariant as “magic”. They see how to proceed once they are given the height invariant, but do not see how they could have come up with the height invariant on their own. Maxiphobic heaps are an alternative to leftist heaps that retain the good qualities of leftist heap, but without the “magic”.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:7bcjnl2b5ko25d5zgdpiqgop/bafkreige4zca3e3krb6ra7nhaoeqlcdahj4cena3hkwlaubohniuzspjey@jpeg)
February 17, 2026 at 9:38 AM
Chris Okasaki on teaching data structures. 🙏
Rare footage of yours truly, like, everyday lately, screaming about AI, COVID, and fascists. (Source: instagram.com/p/DUXmgj8gcI...)
February 11, 2026 at 3:28 PM
Rare footage of yours truly, like, everyday lately, screaming about AI, COVID, and fascists. (Source: instagram.com/p/DUXmgj8gcI...)
Luminy est célèbre pour les sangliers mais on a des chats aussi, par exemple celle-ci, qui est très fluffy et avec un nez en forme de ❤️.
January 28, 2026 at 4:19 PM
Luminy est célèbre pour les sangliers mais on a des chats aussi, par exemple celle-ci, qui est très fluffy et avec un nez en forme de ❤️.
Today I went for the first time to the new site of the I2M maths lab in St-Charles in Marseille, which is in one of the old buildings (i.e., the nice ones that often have pettable cats outside) and it’s super cute. Please notice the tomettes (provençal hexagonal terracotta tiles) on the floor.
January 23, 2026 at 6:05 PM
Today I went for the first time to the new site of the I2M maths lab in St-Charles in Marseille, which is in one of the old buildings (i.e., the nice ones that often have pettable cats outside) and it’s super cute. Please notice the tomettes (provençal hexagonal terracotta tiles) on the floor.
Apparemment il y a un problème de fourmis dans cette station de métro marseillaise. (Normalement c’est les rats.)
![Un panneau de signalisation à LED dans le métro qui dit « NE VOUS SÉPAREZ PAS DE VOS BAGAGES. SIGNALEZ NOTRE TOUT COLIS OUBLIÉ OU [LED hors service] ANTS. »](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:7bcjnl2b5ko25d5zgdpiqgop/bafkreiaytyvnepyg6twbp6jcadurxwww44r5qcuiqmuj7uxw44h4h5edqq@jpeg)
December 21, 2025 at 10:04 AM
Apparemment il y a un problème de fourmis dans cette station de métro marseillaise. (Normalement c’est les rats.)
Eating մանթի [manti] that my Armenian partner made, with madzoun (yogurt) and sumac. 🤤
December 20, 2025 at 7:23 PM
Eating մանթի [manti] that my Armenian partner made, with madzoun (yogurt) and sumac. 🤤
Rare image de Château Gumbear à Marseille.
December 9, 2025 at 12:26 PM
Rare image de Château Gumbear à Marseille.
Voici le communiqué de l’intersyndicale AMU sur la « grande enquête étudiante » de Berton.
December 5, 2025 at 11:53 AM
Voici le communiqué de l’intersyndicale AMU sur la « grande enquête étudiante » de Berton.
Me pretending to be able to play drums.
November 18, 2025 at 12:13 PM
Me pretending to be able to play drums.
Apparently we all missed this particular 2024 journal paper. (This is the “corollary” of a “theorem” which happens to be false.)
June 5, 2025 at 10:49 AM
Apparently we all missed this particular 2024 journal paper. (This is the “corollary” of a “theorem” which happens to be false.)
I had somehow missed until now the paper “Nondeterministic algorithms” by Robert W. Floyd, 1967, which includes nice flowchart algorithms for the 8 queens problem and for finding cycles in a graph, as well as a “determinising” compiler. dl.acm.org/doi/pdf/10.1...
April 29, 2025 at 2:13 PM
I had somehow missed until now the paper “Nondeterministic algorithms” by Robert W. Floyd, 1967, which includes nice flowchart algorithms for the 8 queens problem and for finding cycles in a graph, as well as a “determinising” compiler. dl.acm.org/doi/pdf/10.1...
Cante uno chato de Prouvènço
April 22, 2025 at 10:32 AM
Cante uno chato de Prouvènço
My colleague’s kid drew dinosaurs for me, so it’s only fair I also draw one to reciprocate. 🦕
April 3, 2025 at 12:13 PM
My colleague’s kid drew dinosaurs for me, so it’s only fair I also draw one to reciprocate. 🦕
Écoutez-moi un moment maintenant.
Ça a toujours été sous nos yeux, depuis 1993 !
David Duchovny
David DuchOVNY
David Duch-OVNI
Ça a toujours été sous nos yeux, depuis 1993 !
David Duchovny
David DuchOVNY
David Duch-OVNI
February 18, 2025 at 5:27 PM
Écoutez-moi un moment maintenant.
Ça a toujours été sous nos yeux, depuis 1993 !
David Duchovny
David DuchOVNY
David Duch-OVNI
Ça a toujours été sous nos yeux, depuis 1993 !
David Duchovny
David DuchOVNY
David Duch-OVNI
I love apparently random Italian words in Arabic.
![A Wiktionary page:
بروفا
South Levantine Arabic
Etymology
From Italian prova.
Pronunciation
IPA(key): /broː.va/, [ˈbroː.va]
Audio (al-Lidd):
Noun
بروفا • (brōva) f (plural بروفات (brōvāt))
rehearsal](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:7bcjnl2b5ko25d5zgdpiqgop/bafkreify25wnarr33zyftffbrd5tgas7jqq4q65suq2waawlevkfkx5uwa@jpeg)
February 7, 2025 at 8:42 AM
I love apparently random Italian words in Arabic.
Maltese is unbelievable. Look at this stunning sentence with that Arabic syntax and that vocabulary of mixed Italian (or Sicilian) and Arabic origin. Just amazing. (From youtu.be/s1DyDRn4_Fw)
January 18, 2025 at 8:22 PM
Maltese is unbelievable. Look at this stunning sentence with that Arabic syntax and that vocabulary of mixed Italian (or Sicilian) and Arabic origin. Just amazing. (From youtu.be/s1DyDRn4_Fw)
Love the recursive title, I’m certainly going to publish in this nice journal!
January 8, 2025 at 3:45 PM
Love the recursive title, I’m certainly going to publish in this nice journal!
Anki reminds me that 1000 days ago I resumed studying languages (after a one-year sabbatical).
January 7, 2025 at 2:38 PM
Anki reminds me that 1000 days ago I resumed studying languages (after a one-year sabbatical).
Still working on my French person impression.
December 24, 2024 at 4:54 PM
Still working on my French person impression.
This is a great example of bad user interface: here it appears that the “Feels Like” indicator is a slider that you can adjust, but I assure you it’s read-only! And I bet that in order to unlock it you must modify some obscure configuration file, or buy an alternative 10 $ app.
December 20, 2024 at 10:21 AM
This is a great example of bad user interface: here it appears that the “Feels Like” indicator is a slider that you can adjust, but I assure you it’s read-only! And I bet that in order to unlock it you must modify some obscure configuration file, or buy an alternative 10 $ app.
An old picture of mine, taken during a trip to Gibraltar when I was a visiting PhD student in Sevilla 🇪🇸 in 2011 (damn, that’s so long ago…). The monkey decided autonomously to jump on my shoulder, I did nothing to lure him there. 😊
December 6, 2024 at 9:16 PM
An old picture of mine, taken during a trip to Gibraltar when I was a visiting PhD student in Sevilla 🇪🇸 in 2011 (damn, that’s so long ago…). The monkey decided autonomously to jump on my shoulder, I did nothing to lure him there. 😊
#TodaysNondeterministicAlgorithm solves the longest common subsequence problem (en.wikipedia.org/wiki/Longest...) which is of interest in bioinformatics (and computational linguistics? and more). This is easy for two (or any fixed no. of) sequences, but NP-hard if the number is variable.
![# https://aeporreca.org/nondeterminism
from nondeterminism import *
def guess_subsequence(s):
t = ''
for c in s:
# take character c?
if guess(mode=maximize(len)):
t += c
return t
def is_subsequence(s, t):
i = 0
for c in s:
# look for c in t[i:]
i = t.find(c, i)
if i == -1:
return False
i += 1
return True
@nondeterministic
def lcs(*sequences):
# take the shortest s for efficiency
s = min(sequences, key=len)
t = guess_subsequence(s)
if all(is_subsequence(t, s)
for s in sequences):
return t](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:7bcjnl2b5ko25d5zgdpiqgop/bafkreid2i67ej25va44zcknguphwmkg7inec4is6qfa3otvuxyggxyd43q@jpeg)
December 6, 2024 at 8:39 AM
#TodaysNondeterministicAlgorithm solves the longest common subsequence problem (en.wikipedia.org/wiki/Longest...) which is of interest in bioinformatics (and computational linguistics? and more). This is easy for two (or any fixed no. of) sequences, but NP-hard if the number is variable.