> I have seen it [core memory] in service as recently as 2004 in a telephony control application
1,664 karma · joined January 12, 2014
> I have seen it [core memory] in service as recently as 2004 in a telephony control application
I'd be very interested to hear any thoughts you might have about Jung Chang's book "Wild Swans".
I read this book a year or two ago and learned a lot from it, but I also learned that many people who grew up in China take issue with the author's account. I'd be grateful for any remarks you may be able to share.
The Mathlib Initiative is a new programme of Renaissance Philanthropy. We exist to support Lean's open-source library of formal mathematics known as Mathlib https://leanprover-community.github.io/
Please apply directly at: https://www.renaissancephilanthropy.org/careers/devops-engin...
I have a bookmarklet:
javascript:(function() {window.location=window.location.toString().replace(/^https:\/\/www.youtube\./,'http://fixyt.');})()
and whenever I want to watch a YouTube video, I just click that and enjoy an ad-free experience.
This "dome" is essentially the same issue just with the singularity buried one level deeper: you need to take second derivatives to see it. Indeed a planar cross section containing the vertical axis through its center is a graph of the equation $y^2 = |x|^3$ (up to constants) and this is not twice differentiable at $x = y = 0$. Newtonian mechanics is governed by a second order differential equation, so we need a C^2 regularity assumption to get uniqueness.
So for me there is not really any more philosophically interesting than the question about a particle balancing at the apex of a cone.
It was a project in which we formalised a version of Gromov's (open, ample) h-principle for first order differential relations. Part of the reason it was carried out was to demonstrate what is involved formalising something in differential topology.
This argument thus teaches us even more, namely: the configuration of the four equal-area rectangles orange, yellow, green, pink has the special property that if you widen it to get a square, the extra piece you add also has equal area.
javascript:(function() {window.location=window.location.toString().replace(/^https:\/\/www.youtube\./,'http://fixyt.');})()
The book is based largely on a collection of letters between Vincent and his brother Theo and is quite moving sometimes.
I recommend it!
I'm not quite sure what conclusions to draw.
I always recommend it to anyone teaching young kids to program.
You can find it here: https://www.pytch.org/app/
Ramanujan was of course an extremely talented mathematician but IMHO, there is an unnecessary cult of mystery about him. In particular, there is no mystery as to where this formula comes from: it is obtained from applying a standard technique to a standard formula. Also, it is just one instance, I’ll call it the “k = 6” instance, of a family of such formulae and I’m near-certain the “k = 2” case was known before Ramanujan (on phone or would double check).
In any case, the standard formula is just the series expansion for: n! / sqrt{2πn} (n/e)^n and the standard technique is to raise both sides of a series expansion to some power, k say, multiply out one side, and then take k-th roots again.
In this case we just need to calculate: (1 + 1/12n + 1/288n^2 - 139/51840n^3 + O(1/n^4))^6 = 1 + 1/2n + 1/8n^2 + 1/240n^3 + O(1/n^4)
After taking the 6th root again we multiply inside by 8n^3 (from the LHS) and you get Ramanujan’s formula.
For example, having more free time is probably not adequate compensation for the greenhouse gases emitted (at the societal level at least).
One thing that struck us was just how much it felt like what it is: a piece of France in the tropics. We had just come from Mauritius which felt quite remote but arriving in Réunion suddenly felt like we were back in Europe.
'Like "I could care less", That means you do care, At least a little'
I once hooked a TV remote up to a logic analyser to have a look and here's how the on/off signal looked for this brand: http://olivernash.org/2010/01/03/the-telly-terminator/rc6-6-...
Some further details here: http://olivernash.org/2010/01/03/the-telly-terminator/
Of course it's still possible!
1. https://leanprover-community.github.io/
2. http://wwwf.imperial.ac.uk/~buzzard/xena/natural_number_game...