I had missed these news that a frozen portion of the Niagara Falls had been ice-climbed. By Will Gadd on Jan. 27. This is obviously quite impressive given the weird and dangerous nature of the ice there, which is mostly frozen foam from the nearby waterfall. (I once climbed an easy route on such ice at the Chutes Montmorency, near Québec City, and it felt quite strange…) He even had a special ice hook designed for that climb as he did not trust the usual ice screws. Will Gadd has however climbed much more difficult routes like Helmcken Falls in British Columbia, which may be the hardest mixed route in the World!
Archive for the Mountains Category
The seminar invitation to Edinburgh gave me the opportunity and the excuse for a quick dash to Fort William for a day of ice-climbing on Ben Nevis. The ice conditions were perfect but there was alas too much snowdrift to attempt Point Five Gully, one of the mythical routes on the Ben. (Last time, the ice was not in good conditions.) Instead, we did three pitches on three different routes, one iced rock-face near the CIC hut, the first pitch of Waterfall Gully on Carn Dearg Buttress, and the first pitch of The Curtain, again on Carn Dearg Buttress.
The most difficult climb was the first one, grading about V.5 in Scottish grade, maybe above that as the ice was rather rotten, forcing my guide Ali to place many screws. And forcing me to unscrew them! Then the difficulty got much lower, except for the V.5 start of the Waterfall, where I had to climb with hands an ice pillar as the ice-picks would not get a good grip. Breaking another large pillar in the process, fortunately mostly avoiding being hit. The final climb was quite easy, more of a snow steep slope than a true ice-climb. Too bad the second part of the route was blocked by two fellows who could not move! Anyway, it was another of those rare days on the ice, with enough choice to worry about sharing with other teams, and a terrific guide! And a reasonable day for Scotland with little snow, no rain, plenty of wind and not that cold (except when belaying!).
Yesterday, I was all too briefly in Edinburgh for a few hours, to give a seminar in the School of Mathematics, on the random forests approach to ABC model choice (that was earlier rejected). (The slides are almost surely identical to those used at the NIPS workshop.) One interesting question at the end of the talk was on the potential bias in the posterior predictive expected loss, bias against some model from the collection of models being evaluated for selection. In the sense that the array of summaries used by the random forest could fail to capture features of a particular model and hence discriminate against it. While this is correct, there is no fundamental difference with implementing a posterior probability based on the same summaries. And the posterior predictive expected loss offers the advantage of testing, that is, for representative simulations from each model, of returning the corresponding model prediction error to highlight poor performances on some models. A further discussion over tea led me to ponder whether or not we could expand the use of random forests to Bayesian quantile regression. However, this would imply a monotonicity structure on a collection of random forests, which sounds daunting…
My stay in Edinburgh was quite brief as I drove to the Highlands after the seminar, heading to Fort William, Although the weather was rather ghastly, the traffic was fairly light and I managed to get there unscathed, without hitting any of the deer of Rannoch Mor (saw one dead by the side of the road though…) or the snow banks of the narrow roads along Loch Lubnaig. And, as usual, it still was a pleasant feeling to drive through those places associated with climbs and hikes, Crianlarich, Tyndrum, Bridge of Orchy, and Glencoe. And to get in town early enough to enjoy a quick dinner at The Grog & Gruel, reflecting I must have had half a dozen dinners there with friends (or not) over the years. And drinking a great heather ale to them!