<rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Hacker News: jeffcoat</title><link>https://news.ycombinator.com/user?id=jeffcoat</link><description>Hacker News RSS</description><docs>https://hnrss.org/</docs><generator>hnrss v2.1.1</generator><lastBuildDate>Tue, 05 May 2026 08:36:08 +0000</lastBuildDate><atom:link href="https://hnrss.org/user?id=jeffcoat" rel="self" type="application/rss+xml"></atom:link><item><title><![CDATA[New comment by jeffcoat in "NetHack 5.0.0"]]></title><description><![CDATA[
<p>We can only guess about what's going wrong for you specifically . But I like guessing:<p>(extremely mild spoilers:)<p>- A core skill for Nethack is understanding how much danger you're in at any particular moment. Your comment about soldier ants below tells me you've made good progress here. But you need to recognize when you're in danger and how long you have to deal with that problem before you'll react appropriately.<p>- Nethack's dungeon isn't linear, it branches. (Think of the gnomish mines here, but there are other examples deeper.) When you're getting in over your head in one branch, go back up the stairs and switch to another one.<p>- When you're in immediate danger, Stop. Look through your inventory, consider your options. Think especially about wands, think about ways to write Elbereth, think about scrolls. Think about ways to use diagonal movement to your advantage to get to an escape, or a more defensible position. You have all the time in the world to think. There may not be a solution, but I've died more than a few times with more than one thing in my inventory that could have saved me.<p>- You need to be able to identify some things without waiting for a scroll of identify to fall into your lap. Price is the easiest way to identify the scroll of identify itself. It's also straightforward to learn to identify most useful wands: with spoilers or by experimenting. Engraving with the wand will often give you more information than zapping it. A lot of your early I'm In Danger toolkit will come from wands you've identified this way.<p>Good luck, have fun.<p>(Intermediate player, a few dozen ascensions 20 years ago.)</p>
]]></description><pubDate>Sat, 02 May 2026 22:56:28 +0000</pubDate><link>https://news.ycombinator.com/item?id=47991434</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=47991434</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=47991434</guid></item><item><title><![CDATA[New comment by jeffcoat in "Transponder Landing System enables precision approaches at McMurdo in Antarctica"]]></title><description><![CDATA[
<p>Even switching from magnetic to true is unhelpful close enough to the South pole. All directions are north.<p>We have to switch to "grid" north to make sense of directions there.<p><a href="https://en.wikipedia.org/wiki/Universal_polar_stereographic_coordinate_system" rel="nofollow">https://en.wikipedia.org/wiki/Universal_polar_stereographic_...</a></p>
]]></description><pubDate>Mon, 19 Aug 2024 20:02:31 +0000</pubDate><link>https://news.ycombinator.com/item?id=41294152</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=41294152</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=41294152</guid></item><item><title><![CDATA[New comment by jeffcoat in "No joke: Supreme Court case could take a big bite out of the First Amendment"]]></title><description><![CDATA[
<p>This is amazing. Thank you.</p>
]]></description><pubDate>Sun, 27 Nov 2022 05:20:43 +0000</pubDate><link>https://news.ycombinator.com/item?id=33760638</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=33760638</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=33760638</guid></item><item><title><![CDATA[New comment by jeffcoat in "GNU Units"]]></title><description><![CDATA[
<p>Probably not. Knowing the speed-of-light round trip time to a network location gives you a bound on how much you can improve the performance of remote operations.<p>For example, I'm in Austin, querying a database hosted in Amazon's us-east-1 data center ("Northern Virginia"). Call it 1000 miles away, 2000 mile round trip.<p><pre><code>    You have: 2000 miles
    You want: millilightseconds
            2000 miles = 10.736388 millilightseconds
</code></pre>
If I have a query that's taking < 1ms, no optimization of how that query is executed by the database can possibly improve the overall performance.</p>
]]></description><pubDate>Thu, 07 Jan 2021 17:18:47 +0000</pubDate><link>https://news.ycombinator.com/item?id=25673925</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=25673925</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=25673925</guid></item><item><title><![CDATA[New comment by jeffcoat in "How did anyone do math in Roman numerals? (2017)"]]></title><description><![CDATA[
<p><p><pre><code>  MCMLXVII + LXV
   = MCCCCCCCCCLXVII + LXV (canonicalize)
   = MCCCCCCCCCLXVIILXV    (concatenate)
   = MCCCCCCCCCLLXXVVII    (sort)
   = MCCCCCCCCCLLXXXII     (combine, VV => X)
   = MCCCCCCCCCCXXXII      (... keep combining, LL => C)
   = MMXXXII               (... C{10} => M, nothing left to combine)
   = MMXXXII               (optionally, look for ways to re-write with the subtraction rule)</code></pre></p>
]]></description><pubDate>Tue, 28 Jul 2020 05:40:06 +0000</pubDate><link>https://news.ycombinator.com/item?id=23972641</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=23972641</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=23972641</guid></item><item><title><![CDATA[New comment by jeffcoat in "Hebrew University Archaeologists Find 12th Dead Sea Scrolls Cave"]]></title><description><![CDATA[
<p>I choose to believe it's a prophecy, foretelling the coming of a Universal search engine that will someday make that joke stop working.</p>
]]></description><pubDate>Thu, 09 Feb 2017 13:26:20 +0000</pubDate><link>https://news.ycombinator.com/item?id=13606711</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=13606711</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=13606711</guid></item><item><title><![CDATA[New comment by jeffcoat in "Gimli Glider"]]></title><description><![CDATA[
<p>You're right, thank you.</p>
]]></description><pubDate>Mon, 19 Dec 2016 21:25:52 +0000</pubDate><link>https://news.ycombinator.com/item?id=13215111</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=13215111</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=13215111</guid></item><item><title><![CDATA[New comment by jeffcoat in "Gimli Glider"]]></title><description><![CDATA[
<p>You're recalling a different incident: engine-out problems are a routine part of flight training at every level.<p>You're thinking of <a href="https://en.wikipedia.org/wiki/United_Airlines_Flight_232" rel="nofollow">https://en.wikipedia.org/wiki/United_Airlines_Flight_232</a><p>where so much of the plane broke that they had to invent a new way to fly it.<p>I can't turn up a reference right now, but like you say, in the next few years that failure was repeatedly simulated, and all the simulated planes crashed.<p>(IIRC, Haynes declined to try his hand at any of the simulations, explaining that the one time when it really mattered was enough for him.)</p>
]]></description><pubDate>Mon, 19 Dec 2016 08:56:21 +0000</pubDate><link>https://news.ycombinator.com/item?id=13210316</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=13210316</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=13210316</guid></item><item><title><![CDATA[New comment by jeffcoat in "Coq 8.6 is out"]]></title><description><![CDATA[
<p>Certified Programming with Dependent Types<p><a href="http://adam.chlipala.net/cpdt/" rel="nofollow">http://adam.chlipala.net/cpdt/</a></p>
]]></description><pubDate>Wed, 14 Dec 2016 18:34:51 +0000</pubDate><link>https://news.ycombinator.com/item?id=13178411</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=13178411</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=13178411</guid></item><item><title><![CDATA[New comment by jeffcoat in "Elementary proof that e is irrational"]]></title><description><![CDATA[
<p>You'll also need to know that e^x = sum{0 -> infinity} x^n / n!.</p>
]]></description><pubDate>Tue, 13 Dec 2016 17:56:04 +0000</pubDate><link>https://news.ycombinator.com/item?id=13168839</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=13168839</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=13168839</guid></item><item><title><![CDATA[New comment by jeffcoat in "The Untold Story Behind Saudi Arabia’s U.S. Treasury Holdings"]]></title><description><![CDATA[
<p>Not so stupid: Start with the phrase "Hoteling's rule" for a century of academic analysis of that question.<p>If you own an oil field, you have to balance a number of factors:<p>* How is the price of oil changing, relative to overall inflation? You mentioned this one.<p>But also,<p>* Are technological improvements (either increasing the total amount of extractable oil in the world, or outright oil replacements) going to dramatically lower the price if I wait too long?<p>* Is it still going to be my oil next year, or am I going to be first against the wall when the next revolution comes?<p>My (unsophisticated, outsider) opinion is that if you see oil-producing countries selling as quickly as they can, that's weak evidence that they're worried about the last two bullets.</p>
]]></description><pubDate>Tue, 31 May 2016 19:20:04 +0000</pubDate><link>https://news.ycombinator.com/item?id=11809312</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=11809312</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=11809312</guid></item><item><title><![CDATA[New comment by jeffcoat in "The King of Human Error: Michael Lewis on Daniel Kahneman (2011)"]]></title><description><![CDATA[
<p>I enjoyed it: not a sports fan, knew little of baseball except that the one game pro game I've seen in person was super-boring [to me].<p>_Moneyball_ isn't about baseball so much as it's about how easy it is for humans to be tricked by our intuitions and habits. Moneyball talks about baseball from the point of view of someone who everyone just assumed would be good -- and wasn't -- as he's trying to make more and more objective assessments of players, and wielding his conclusions against competing,  more traditional managers.</p>
]]></description><pubDate>Thu, 03 Mar 2016 08:01:32 +0000</pubDate><link>https://news.ycombinator.com/item?id=11215587</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=11215587</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=11215587</guid></item><item><title><![CDATA[New comment by jeffcoat in "The Work of John Milnor, a giant in modern mathematics [pdf]"]]></title><description><![CDATA[
<p>It's because "latitude lines" aren't really lines in this context (except the one at the equator).<p>If you took two points from one of those latitude "lines", you'd always be able to find a shorter path between them than the path along the latitude. If you take the shortest path between the two points and extend it all the way around the sphere, you'll end up with a great circle. That great circle is an actual "line" in this geometry.<p><a href="https://en.wikipedia.org/wiki/Spherical_geometry" rel="nofollow">https://en.wikipedia.org/wiki/Spherical_geometry</a></p>
]]></description><pubDate>Wed, 17 Feb 2016 19:00:27 +0000</pubDate><link>https://news.ycombinator.com/item?id=11120286</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=11120286</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=11120286</guid></item><item><title><![CDATA[New comment by jeffcoat in "Dozens of oil tankers cluster off the coast of Texas due to oil price fall"]]></title><description><![CDATA[
<p>It's obvious that moving oil in space helps, right? You move the resource from a place it's relatively plentiful to a different place where oil is relatively scarce. Say, from the Persian Gulf to Australia.<p>The same thing is happening here:<p>These ships are trying to move oil from a <i>time</i> when oil is relatively plentiful to a time when it's relatively scarce. It's riskier, but if they succeed, everybody wins: they make money, and they do it by lessening that future scarcity.</p>
]]></description><pubDate>Fri, 13 Nov 2015 22:21:20 +0000</pubDate><link>https://news.ycombinator.com/item?id=10562773</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=10562773</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=10562773</guid></item><item><title><![CDATA[New comment by jeffcoat in "Foundations of probability theory"]]></title><description><![CDATA[
<p>All of this is fine for real-valued inputs and outcomes. It's the number of events (coin flips, measurements, etc) that we're restricting to be countable.</p>
]]></description><pubDate>Fri, 02 Oct 2015 19:37:58 +0000</pubDate><link>https://news.ycombinator.com/item?id=10320777</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=10320777</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=10320777</guid></item><item><title><![CDATA[New comment by jeffcoat in "Albert Woodfox's Forty Years in Solitary Confinement"]]></title><description><![CDATA[
<p>I think I know what you're getting at, but the problem here is that prosecutors have some discretion.<p>The chain of thought that goes<p><pre><code>  I only prosecute worthy cases

  => I picked those cases because these people are guilty,
      and need to be convicted for the good of society 

  => my conviction rate is exactly the same as my 
     'I made a better world' rate.
</code></pre>
must be very tempting.  Wrong, but tempting.</p>
]]></description><pubDate>Fri, 19 Jun 2015 07:18:54 +0000</pubDate><link>https://news.ycombinator.com/item?id=9743393</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=9743393</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=9743393</guid></item><item><title><![CDATA[New comment by jeffcoat in "TSA failure: Investigators able to smuggle weapons past checks in 95% of tests"]]></title><description><![CDATA[
<p>ABC ran pretty much this same story in 2010:<p><a href="http://abcnews.go.com/Blotter/loaded-gun-slips-past-tsa-screeners/story?id=12412458" rel="nofollow">http://abcnews.go.com/Blotter/loaded-gun-slips-past-tsa-scre...</a><p><pre><code>  According to one report, undercover TSA agents
  testing security at a Newark airport terminal on
  one day in 2006 found that TSA screeners failed
  to detect concealed bombs and guns 20 out of 22 times.

  A 2007 government audit leaked to USA Today revealed
  that undercover agents were successful slipping simulated
  explosives and bomb parts through Los Angeles's LAX
  airport in 50 out of 70 attempts, and at Chicago's
  O'Hare airport agents made 75 attempts and succeeded
  in getting through undetected 45 times.</code></pre></p>
]]></description><pubDate>Mon, 01 Jun 2015 17:34:11 +0000</pubDate><link>https://news.ycombinator.com/item?id=9640545</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=9640545</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=9640545</guid></item><item><title><![CDATA[New comment by jeffcoat in "GC Tuning Confessions of a Performance Engineer"]]></title><description><![CDATA[
<p>The slides are interesting enough that I went looking to see if the actual talk that goes with them was online anywhere; found it at<p><a href="http://chariotsolutions.com/screencast/philly-ete-2015-7-monica-beckwith-gc-tuning-confessions-of-a-performance-engineer/" rel="nofollow">http://chariotsolutions.com/screencast/philly-ete-2015-7-mon...</a></p>
]]></description><pubDate>Fri, 29 May 2015 16:02:58 +0000</pubDate><link>https://news.ycombinator.com/item?id=9625395</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=9625395</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=9625395</guid></item><item><title><![CDATA[New comment by jeffcoat in "Please don't denigrate what a beginner is currently learning"]]></title><description><![CDATA[
<p>It's tough being smart and influential: your [Dijkstra's] successes and mistakes end up going through the same megaphone.</p>
]]></description><pubDate>Mon, 08 Dec 2014 01:31:05 +0000</pubDate><link>https://news.ycombinator.com/item?id=8714447</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=8714447</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=8714447</guid></item><item><title><![CDATA[How I Teach When I Really Want My Students to Learn]]></title><description><![CDATA[
<p>Article URL: <a href="http://econlog.econlib.org/archives/2014/07/how_i_teach_whe.html">http://econlog.econlib.org/archives/2014/07/how_i_teach_whe.html</a></p>
<p>Comments URL: <a href="https://news.ycombinator.com/item?id=8407566">https://news.ycombinator.com/item?id=8407566</a></p>
<p>Points: 2</p>
<p># Comments: 0</p>
]]></description><pubDate>Fri, 03 Oct 2014 20:46:27 +0000</pubDate><link>http://econlog.econlib.org/archives/2014/07/how_i_teach_whe.html</link><dc:creator>jeffcoat</dc:creator><comments>https://news.ycombinator.com/item?id=8407566</comments><guid isPermaLink="false">https://news.ycombinator.com/item?id=8407566</guid></item></channel></rss>