Cryptography Updated +Created
csvtool Updated +Created
A compiled executable under /usr/bin/csvtool, has an Ubuntu 23.04 package: manpages.ubuntu.com/manpages/lunar/en/man1/csvtool.1.html
There seems to be no sane filtering mechanism however: stackoverflow.com/questions/46540752/using-csvtool-call-to-filter-csv-in-bash
csvtools Updated +Created
A fast version of a somewhat subset of csvkit, written in C.
Build failed with undefined reference to pcre_config on Ubuntu 23.04: github.com/DavyLandman/csvtools/issues/18
Unfortunately it is lacking some basic options, like optional header + selecting column by index on csvgrep (though csvcut has it). The project seems kind of dead.
Also unclear if it allows to filter + print only selected columns.
Cycle notation Updated +Created
A concise to describe a specific permutation.
A permutation group can then be described in terms of the generating set of a group of specific elements given in cycle notation.
E.g. en.wikipedia.org/w/index.php?title=Mathieu_group&oldid=1034060469#Permutation_groups mentions that the Mathieu group is generated by three elements:
  • (0123456789a)
  • (0b)(1a)(25)(37)(48)(69)
  • (26a7)(3945)
which feels quite compact for a simple group with 95040 elements, doesn't it!
Invalid Bitcoin transaction script Updated +Created
Two photon interference experiment Updated +Created
The basic experiment for a photonic quantum computer.
Can be achieved in two ways it seems:
Animation of Hong-Ou-Mandel Effect on a silicon like structure by Quantum Light University of Sheffield (2014): www.youtube.com/watch?v=ld2r2IMt4vg No maths, but gives the result clear: the photons are always on the same side.
Video 1.
Quantum Computing with Light by Quantum Light University of Sheffield (2015)
Source. Animation of in-silicon single photon device with brief description of emitting and receiving elements. Mentions:
Video 2.
Quantum Optics - Beam splitter in quantum optics by Alain Aspect (2017)
Source. More theoretical approach.
Video 3.
Building a Quantum Computer Out of Light by whentheappledrops (2014)
Source. Yada yada yada, then at youtu.be/ofg335d3BJ8?t=341 shows optical table and it starts being worth it. Jacques Carolan from the University of Bristol goes through their setup which injects 5 photons into a 21-way experiment.
Alan Watts controlled dream of life talk Updated +Created
Goes along: if you could control your life multiple times to be perfect, you would eventually get tired of paradise, and you would go further and further into creating uncertain worlds with some suffering, until you would reach the current real world.
Very similar to The Matrix (1999) when Agent Smith talks about the failed Paradise Matrix shown at www.youtube.com/watch?v=9Qs3GlNZMhY:
Did you know that the first Matrix was designed to be a perfect human world where none suffered, where everyone would be happy? It was a disaster. No one would accept the program. Entire crops were lost. Some believed that we lacked the programming language to describe your "perfect world". But I believe that, as a species, human beings define their reality through misery and suffering. So the perfect world was a dream that your primitive cerebrum kept trying to wake up from.
Video 1.
Alan Watts' "The dream of life" talk
. Source.
Ordinal ruleset inscription collection Updated +Created
This section is about groups of ordinal ruleset inscription that share a theme and were presumably created by a single entity.
Cycle graph (algebra) Updated +Created
How to build it: math.stackexchange.com/questions/3137319/how-in-general-does-one-construct-a-cycle-graph-for-a-group/3162746#3162746 good answer with ASCII art. You basically just pick each element, and repeatedly apply it, and remove any path that has a longer version.
Immediately gives the generating set of a group by looking at elements adjacent to the origin, and more generally the order of each element.
TODO uniqueness: can two different groups have the same cycle graph? It does not seem to tell us how every element interact with every other element, only with itself. This is in contrast with the Cayley graph, which more accurately describes group structure (but does not give the order of elements as directly), so feels like it won't be unique.
Davinci Jeremie Updated +Created
Video 1.
Just buy $1 worth of Bitcoin please! by Davinci Jeremie (2013)
Source.
Day Updated +Created
Front-end web framework Updated +Created
You need those because it is hard to do the following:
  • client JavaScript sends a request to server
  • server sends back data
  • client updates what the user sees
This is hard to do notably because when the update happens, several things might need to change on the webpage at the same time.
Notably, new elements might need to be added to the webpage, which in turn means that new bindings such as button clicks have to be added to those, in a way that keeps the page working.
The only way to do this basically is to have a functional dependency graph that keeps everything in the page in working state as updates come.
OP_INVALIDOPCODE Updated +Created
Ubuntu Updated +Created
Ciro Santilli's Linux distro of choice as of 2019.
It ain't perfect, but it's decent enough.
The greatest advantage of it being that it has the likely largest desktop user base, and therefore the highest likelihood that your problems are solved on Ask Ubuntu, and goes together with Ciro's philosophy that "people should do everything in the same way to factor stuff out", especially the open source losers.
Ciro considers that the killer flaw of Ubuntu, and most desktop distros of 2020, is that no one under the Sun knows how to build them fully from source: Linux distribution buildable from source. This is why Ciro based the Linux Kernel Module Cheat on Buildroot, see also: Linux distribution buildable from source.
77822fd6663c665104119cb7635352756dfc50da76a92d417ec1a12c518fad69 Updated +Created
Ouptut 0 disassembles as:
OP_IF OP_INVALIDOPCODE 4effffffff <large constant> OP_ENDIF
The large constant contains an ASCII Bitcoin Core patch entitled Remove (SINGLE|DOUBLE)BYTE so presumably this is a proof of concept:
From a3a61fef43309b9fb23225df7910b03afc5465b9 Mon Sep 17 00:00:00 2001
From: Satoshi Nakamoto <satoshin@gmx.com>
Date: Mon, 12 Aug 2013 02:28:02 -0200
Subject: [PATCH] Remove (SINGLE|DOUBLE)BYTE

I removed this from Bitcoin in f1e1fb4bdef878c8fc1564fa418d44e7541a7e83
in Sept 7 2010, almost three years ago. Be warned that I have not
actually tested this patch.
---
 backends/bitcoind/deserialize.py |    8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/backends/bitcoind/deserialize.py b/backends/bitcoind/deserialize.py
index 6620583..89b9b1b 100644
--- a/backends/bitcoind/deserialize.py
+++ b/backends/bitcoind/deserialize.py
@@ -280,10 +280,8 @@ opcodes = Enumeration("Opcodes", [
     "OP_WITHIN", "OP_RIPEMD160", "OP_SHA1", "OP_SHA256", "OP_HASH160",
     "OP_HASH256", "OP_CODESEPARATOR", "OP_CHECKSIG", "OP_CHECKSIGVERIFY", "OP_CHECKMULTISIG",
     "OP_CHECKMULTISIGVERIFY",
-    ("OP_SINGLEBYTE_END", 0xF0),
-    ("OP_DOUBLEBYTE_BEGIN", 0xF000),
     "OP_PUBKEY", "OP_PUBKEYHASH",
-    ("OP_INVALIDOPCODE", 0xFFFF),
+    ("OP_INVALIDOPCODE", 0xFF),
 ])
 
 
@@ -293,10 +291,6 @@ def script_GetOp(bytes):
         vch = None
         opcode = ord(bytes[i])
         i += 1
-        if opcode >= opcodes.OP_SINGLEBYTE_END and i < len(bytes):
-            opcode <<= 8
-            opcode |= ord(bytes[i])
-            i += 1
 
         if opcode <= opcodes.OP_PUSHDATA4:
             nSize = opcode
-- 
1.7.9.4
bitcointalk.org/index.php?topic=5231222.0 duscusses what happens if there is an invalid opcode in a branch that is not taken.
Definition of the orthogonal group Updated +Created
Intuitive definition: real group of rotations + reflections.
Mathematical definition that most directly represents this: the orthogonal group is the group of all matrices that preserve the dot product.
Del Updated +Created
Oh, and if it weren't enough, mathematicians have a separate name for the damned nabla symbol : "del" instead of "nabla".
TODO why is it called "Del"? Is is because it is an inverted uppercase delta?

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