Computer Olympiad Updated +Created
Ah, shame, they are a bit weak.
Gospel of Matthew Updated +Created
The first chapter of the New Testament.
Ben Goertzel Updated +Created
www.reddit.com/r/artificial/comments/b38hbk/what_do_my_fellow_ai_researchers_think_of_ben/ What do my fellow AI researchers think of Ben Goertzel and his research?
.text section Updated +Created
Now that we've done one section manually, let's graduate and use the readelf -S of the other sections:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 2] .text             PROGBITS         0000000000000000  00000210
       0000000000000027  0000000000000000  AX       0     0     16
.text is executable but not writable: if we try to write to it Linux segfaults. Let's see if we really have some code there:
objdump -d hello_world.o
gives:
hello_world.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <_start>:
   0:       b8 01 00 00 00          mov    $0x1,%eax
   5:       bf 01 00 00 00          mov    $0x1,%edi
   a:       48 be 00 00 00 00 00    movabs $0x0,%rsi
  11:       00 00 00
  14:       ba 0d 00 00 00          mov    $0xd,%edx
  19:       0f 05                   syscall
  1b:       b8 3c 00 00 00          mov    $0x3c,%eax
  20:       bf 00 00 00 00          mov    $0x0,%edi
  25:       0f 05                   syscall
If we grep b8 01 00 00 on the hd, we see that this only occurs at 00000210, which is what the section says. And the Size is 27, which matches as well. So we must be talking about the right section.
This looks like the right code: a write followed by an exit.
The most interesting part is line a which does:
movabs $0x0,%rsi
to pass the address of the string to the system call. Currently, the 0x0 is just a placeholder. After linking happens, it will be modified to contain:
4000ba: 48 be d8 00 60 00 00    movabs $0x6000d8,%rsi
This modification is possible because of the data of the .rela.text section.
I Updated +Created
J Updated +Created
K Updated +Created
M Updated +Created
W Updated +Created
Y Updated +Created
Z Updated +Created
Et aliī Updated +Created
Two different Lie groups can have the same Lie algebra Updated +Created
The most important example is perhaps and , both of which have the same Lie algebra, but are not isomorphic.
Superfluid helium Updated +Created
Ordnance Survey Updated +Created
Has some of the best map data available for the United Kingdom, but their data appears to be proprietary?
1908 Nobel Prize in Chemistry Updated +Created
Why not a balanced tree Updated +Created
Learned readers will ask themselves: so why use an unbalanced tree instead of balanced one, which offers better asymptotic times en.wikipedia.org/wiki/Self-balancing_binary_search_tree?
Likely:
  • the maximum number of entries is small enough due to memory size limitations, that we won't waste too much memory with the root directory entry
  • different entries would have different levels, and thus different access times
  • tree rotations would likely make caching more complicated
XML Updated +Created
Lagrangian density Updated +Created
When we particles particles, the action is obtained by integrating the Lagrangian over time:
In the case of field however, we can expand the Lagrangian out further, to also integrate over the space coordinates and their derivatives.
Since we are now working with something that gets integrated over space to obtain the total action, much like density would be integrated over space to obtain a total mass, the name "Lagrangian density" is fitting.
E.g. for a 2-dimensional field :
Of course, if we were to write it like that all the time we would go mad, so we can just write a much more condensed vectorized version using the gradient with :
And in the context of special relativity, people condense that even further by adding to the spacetime Four-vector as well, so you don't even need to write that separate pesky .
The main point of talking about the Lagrangian density instead of a Lagrangian for fields is likely that it treats space and time in a more uniform way, which is a basic requirement of special relativity: we have to be able to mix them up somehow to do Lorentz transformations. Notably, this is a key ingredient in a/the formulation of quantum field theory.

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