Posted on Jan 18, 2009

Coin Survival Trip (Fuzzified Path Finding Algorithm)

A friend of mine is back-packing in vietnam these days, and wrote me an adorable mail about his impressions and experiences. He mentions a method of traveling around, he himself calls “Coin-survival-trip”. I’m citing his german annotations (translation follows below):

Wir haben ein wirklich nettes Vietnam-Reisebegleiter-Buch. Allerdings: Was machen Experten, wie wir? Richtig, wir führen in Hanoi den „Coin-survival-trip“ ein. Dies ist mindestens genau so spannend, wie einfach zu erklären.

Ziel des Spiels ist es, die nächste zusagende Bierbar zu finden. Mithilfe eines Münzwurfes wird an Kreuzungen entschieden, ob nach links oder rechts abgebogen wird. Gibt es die Möglichkeit weiter geradeaus zu wandern entscheidet das Bequemlichkeit-Zufallsprinzip. Tritt dies in Kraft wird keine Münze geworfen, sondern weiter marschiert.

Translation to english:

We’ve got a lovely vietnam guide book, but what would experts, like us, use instead? Yes, we’re going to establish the “coin-survival-trip” in Hanoi. This is certainly as much fun as easy to explain.

Aim of the game is to find the nearest suitable bar. Entering a crossing, a coin toss decides wether you’ll have to turn left or right. If there’s the possibility to walk straight ahead, a random accomodativeness-principle is used. If this principle comes into effect, no coin tossing is used.

If you’re ever on a journey yourself, spread this idea and do a coin-survival-trip; it’s such a lovely idea, it has to go ’round the world!

Posted on Jan 17, 2009

Fedora Yellow Update Manager (yum) Database-Errors (quick fix)

I had a strange error within my last yum update command. I got these error

rpmdb: Thread/process xxxxx/yyyyyyyyyy failed:
Thread died in Berkeley DB library

and yum stuck in the mid of the update process. This might have been due to an compromised ext-filesystem, as my laptop didn’t shutdown properly and maybe the journal got cluttered.

However, there is an easy way to get thinks back to a working state (at least for me), which might help others:

rm -f /var/lib/rpm/__db*
rpm –rebuilddb

yum clean all
yum check-update

The first two lines remove the old database entries and rebuild the Berkely database. Make sure, that there are no other yum-services running while rebuilding the database (at least this is, what has been said in the bug-reports). The second two lines clean the yum cache and update the package lists. Yum should run without database errors now.

The error has multiple hits (though it’s obviously not a bug) on the Fedora bug-tracker (bug#471411, bug#468437, bug#462314, bug#479818 and bug#45303)