skip to main content.

posts for july 2014.

yesterday, we visited the pizol. getting up was quite an adventure, though; we first travelled via train to bad ragaz, from where claimed bus 456 (a postauto) proceeds to the cable car station. unfortunately, as it turned out, the bus is only going during winter season. as we were waiting where it should leave, we noticed another small bus with “pizol” largely printed on it leaving at the designated time. the bus was hidden behind another postauto when we got out of the train station, so we only noticed it when it was leaving. since we weren’t the only ones standing at the postauto stop waiting for bus 456, we were a bit confused, and finally went to ask in the train station. turns out, they knew that the bus was still written on incorrectly and already passed the message on several times, but nothing happened. so we waited one hour for the next bus (walking would have taken around 40 minutes, but that’s not too much fun at over 30 degrees in the sun). well, when the (private) pizol bus finally came back, we also tried to inform the driver, who apparently never before heard about this problem. he also mentioned that from next year on, there will be a postauto also during summer… well, we hope that maybe now someone will put up a sign at the postauto stop that the bus is currently departing from somewhere else…

anyway, we finally took up the cable cars to laufböden, from where we wanted to walk the panorama trail (should be around 60 minutes). interestingly, the only sign up there pointing to the destination of the panorama trail said it would take 20 minutes. with no real different choice, we started walking that direction, until after 50 meters or so we found another sign, splitting up between the direct route (“standart-weg”) and the panorama trail. we continued the panoramic trail, though in the end we noticed we apparently screwed something up, as when we arrived at a lake inbetween, we saw that the panoramic trail leaving from there to our starting point left in another direction… whatever… anyway, we had a nice view, and up there the temperature was really nice and bearable. we also were able to put our feet into the lake, which was very refreshing. after circling the lake, we continued the trail to the pizolhütte where we had lunch, and finally proceeded down.

overall it was a very nice excursion, except that getting there (and also getting back to the train station) via public transport is apparently somewhat more complicated…

i’m very happy to announce that the lattice reduction library plll has finally been released as open source under the MIT license by the university of zurich. during my recent years at the university of zurich, i’ve been mainly working on this c++ library. it supports a wide range of lattice reduction algorithms and svp solvers, and makes heavy use of c++ templates and has support for c++11‘s move operations.

in 2011, i began implementing it since i wasn’t happy with some of the behavior of ntl‘s lattice reduction algorithms (mainly: in case of fatal numerical instability, they just terminate the program, and the library cannot be used in more than one thread at the same time). back then, ntl’s main competior fplll didn’t support bkz reduction, so i decided to try things out myself. after some time (years), my initial experiments grew into a full library supporting not only the more common lll and bkz algorithms as well as svp solving by enumeration, but also several different algorithms for lattice reduction and svp solving which are described in literature but for which it is sometimes quite hard to find a working implementation of. though the implementations of these algorithms are still more on the experimental side, the basic algorithms such as lll, bkz, potentially combined with deep insertions, and enumeration, are well-tested over the years. (in fact, some large-scale lattice reduction experiments i did for these algorithms yielded some results in the svp challenge’s hall of fame).

in case you’re interested in this library, feel free to play around with it! in case you have any questions, encounter problems, or want to give feedback, feel free to contact me by email.