karlding

I wonder how this will affect adoption of CockroachDB [1], which was inspired by Spanner and supposedly an open source equivalent. I'd imagine that Spanner is a rather compelling choice, since they don't have to host it themselves. As far as I know, CockroachDB currently does not support providing CockroachDB as a service (but it is on their roadmap) [2].

[1] https://www.cockroachlabs.com/docs/frequently-asked-question...

[2] https://www.cockroachlabs.com/docs/frequently-asked-question...

I read through the blog post and skimmed the project site, but it never occurred to me to check the README. Thanks!

Was the name was inspired by Charlotte "Lotte" Reiniger [1], one of the pioneers of silhouette animation? If not, that's one happy coincidence!

[1] https://en.wikipedia.org/wiki/Lotte_Reiniger

I believe World Solar Challenge regulations [1] are now only allowing a maximum of 5m^2 for Cruiser class vehicles (mounted to the car itself).

  +------------+-------------------+---------------------------------+
  | Class      | PV Cell Chemistry | Allowable Total Cell Area (m^2) |
  +------------+-------------------+---------------------------------+
  | Challenger | Si                | 4.000                           |
  +------------+-------------------+---------------------------------+
  | Challenger | thin film GaAs    | 3.560                           |
  +------------+-------------------+---------------------------------+
  | Challenger | multijunction     | 2.640                           |
  +------------+-------------------+---------------------------------+
  | Cruiser    | Si                | 5.000                           |
  +------------+-------------------+---------------------------------+
  | Cruiser    | thin film GaAs    | 4.440                           |
  +------------+-------------------+---------------------------------+
  | Cruiser    | multijunction     | 3.300                           |
  +------------+-------------------+---------------------------------+

And then a supplemental array may be carried inside the vehicle only for charging (2m^2 for Si, 1.78m^2 for thin film GaAs, and 1.32m^2 for multijunction). So the total area actually on the cars at WSC would be less.

But yeah, as a member of one of these solar car teams, it is hard to design a net-positive vehicle that doesn't resemble a UFO. Cruiser class is a move in that direction, but the most successful teams have an aerobody and chassis optimized to be as flat as possible, to get the most out of their array.

[1] https://www.worldsolarchallenge.org/files/1504_2017_bwsc_reg...

I've been using the free-tier of Classeur [1] for taking notes during class, which I then export to a PDF. It's basically an online Math/Mardown editor with pretty much the same feature-set.

Maybe I'll try this out and see how I like it.

[1] http://classeur.io/

No, graph planarity can be determined using Kuratowski's theorem, which essentially states that a graph is planar if and only if it doesn't contain K_{5} or K_{3, 3}.

I believe the planarity test algorithm has been improved, such that it can be done in O(n) using the edge addition method [1].

[1] http://www.drdobbs.com/planarity-by-edge-addition/184406070

Technically, you could map jk or something in your ~/.vimrc in order to exit insertion mode, which would avoid the whole issue.

  :imap jk <Esc>

(I don't personally use this, but one of my friends swears by it)

Unless they've recently made changes, their OS firmware is actually built on top of FreeRTOS, with a bunch of backported features and memory optimizations for the lower-end and first-generation devices.

I think the most impressive engineering feat is what they're able to accomplish in their software, given their hardware limitations.

It's a Google Search feature [0]. Add "cache:" in front of the URL you search on Google to try and view the cached version.

Since most browsers nowadays implement an "omnibar" with Google as the default search provider, it appears seamless and performs the redirect.

[0] https://support.google.com/websearch/answer/2466433?hl=en

One problem with archive.org is that it retroactively obeys the robots.txt file, even if the files have been spidered and archived [0].

For example, consider the case when a new domain owner attempts to block all bots from spidering their site, by adding something like this to their robots.txt file

    User-agent: *
    Disallow: /

This is actually a fairly common case when domain resellers purchase expired domains.

Now when you try to visit the archived link, because the live robots.txt file disallows bots, you won't be able to access the archived site (which may have been owned by someone completely different).

[0] https://archive.org/post/406632/why-does-the-wayback-machine...

There was a post on HN [0] a few years back about the Dalvik patch that Facebook used for their Android app, due to the large number of methods [1] the app had. This was causing issues on the older Gingerbread devices, so their solution was to modify the internals of the Dalvik VM while it was running their code to increase the buffer size.

[0] https://news.ycombinator.com/item?id=5321634

[1] https://www.facebook.com/notes/facebook-engineering/under-th...

You used to be able to do this with the Facebook Query Language (FQL) that Facebook exposed, sending something like this query to the FQL endpoint.

   SELECT uid, name, online_presence
   FROM user
   WHERE online_presence IN ('active', 'idle')
   AND uid IN (
     SELECT uid2 FROM friend WHERE uid1 = me()
   )

Unfortunately, the current version of the Facebook Graph API[0] doesn't have the online_presence field, so this is no longer possible. Maybe the Graph API will be updated in the future to also return the online_presence fields?

[0] https://developers.facebook.com/docs/graph-api/reference/v2....