Tag: trips

children were cool

chinese wisdom, from suzhou. i thought that chinglish would probably be a “language” soon to be extinct, as the dictionaries and automatic translators got better. but after almost 2 years of living here, i don’t think that’s the case. chinglish is alive and well, omnipresent in every restaurant menu, advertising banner, school book, product description… sometimes it’s funny, sometimes cryptic, sometimes technically correct but not so polite… but definitely here to stay!

traveling

… and we’re back!

kuala lumpur, singapore and malacca were a blast. many pictures and field notes to follow :)

geek just life

mr. cook, we have a problem.

when i failed to join the air force and had to choose another career, i picked informatics, journalism and astronomy, all in the same application form – that’s how clueless i was towards my future. in the end, informatics won, and 7 years later, here i am, still clueless but with an engineering degree! :)
every now and then, on the most improbable situations, the informatics/mathematics part comes in handy, like for instance (and ironically) when i have to fly.

here’s the formal definition of a common problem, known as packing. the next time your mom tells you to stop procrastinating on your packing duties, you can properly explain her how hard that is – and hopefully delay the task a little longer!

you have n kinds of items, 1 through n. each item j has a value (sentimental or of importance) p_j and a weight w_j. the maximum weight one can carry in the suitcase is c, and according to british airways, c=23 kgs.
the number of each kind of item in the suitcase, x_j, is restricted to zero or one (for simplicity purposes).
mathematically the problem can be formulated as:
maximize $\sum_{j=1}^n p_j x_j.$
subject to $\sum_{j=1}^n w_j x_j \le c, \quad \quad x_j = 0\;\mbox{or}\;1, \quad j=1,\dots,n.$

this is called a 0-1-knapsack problem, which is known to be a np-complete problem. np stands for non-deterministic polynomial time… and that translates into “very hard & time-consuming problem”.

another np-complete problem is called bin packing, which consists of neatly placing different volumes in as less bins as possible. no time-efficient solution has been discovered for these problems.

so there you go. combine the two and you have packing! :D

(and now, back to the suitcases…)

ps – images from wikipedia, more on the subject here.
ps2 – who was stephen cook?

Post author By ana
Post date January 5, 2008
No Comments on mr. cook, we have a problem.

in china

a thousand islands

we went to qiandao (literally, thousand islands) lake last weekend. it’s a man-made lake near hangzhou, that resulted from the construction of a hydroelectric station: when the water rose, +1000 “islands” were born, hence the name.

the landscape is impressive, if sad.
while the ferry hops between the different islands (curiously themed and mildly touristically explored), one has the feeling of floating between mountain tops, cirurgically cut with level lines.

(more photos, on flickr.)