There are a many of news articles and youtube videos which present HFT as a bad thing.
Since large orders are filled by different markets, anyone who has studied the mechanisms via which these orders are full-filled can theoretically arrive at a strategy that might be profitable.
Overtime, more and more people will learn these things and it will no longer be a profitable strategy to implement - this is sort of like the "January Effect" described in the book named intelligent investor.
I don't understand why HFT has to be blamed for a difference in prices across multiple markets. I read somewhere that REGNMS caused market fragmentation and HFT traders spend time studying the current markets and identify inefficiencies that can be used to make profitable trades.
This Reuters article is like an advertisement for the IEX trading platform. IEX figured out a certain way to beat the other algorithms and they told Reuters about it. Now that everyone knows it, I think, pretty soon other algorithm developers will modify their implementations.
Overall, I think that HFT is basically algorithmic trading, but which needs more investment (for renting/buying server/connectivity) and more time/interest (for studying and understanding the order placement/fulfilment mechanisms involved).
When I was in India I got antibiotics OTC a few times for myself after I self diagnosed using the internet. Because my mum went to med-school I was always very aware about the need to complete the course. I am sure that not everybody is as careful:
http://ibnlive.in.com/blogs/shalini/211/65030/anitbiotic-res...
In India there are lots of doctors running small individual practices, due to this for simple diagnosis and prescription they would charge a small fee in cash and be done with it. Infact, I know for a fact that the Ayurvedic doctor near our house used to charge less than the standard Doctor.
When I came to the US, I found things here to be more restrictive - but I guess in the interest of safety we have to accept these restrictions.
activesupport-3.2.11/lib/active_support/core_ext/hash/conversions.rb has a -- DISALLOWED_XML_TYPES = %w(symbol yaml) -- which is used by its def typecast_xml_value to raise the exception.
I don't see these lines of code in activesupport-3.0.3/lib/active_support/core_ext/hash/conversions.rb
In my case I could upgrade to 3.2.11.
In your case, I am guessing you added the lines of code that disable xml and yaml parameter parsing to an initializer (or application.rb). This way, activesupport simply wouldn't try to convert the parameter value in question into a ruby object.
This way a vulnerable server's log file shows something like give below(ie. the Time object was actually created from the yaml):
Started POST "/users/sign_in" for 127.0.0.1 at 2013-01-10 00:26:40 -0500
Processing by Devise::SessionsController#create as /
Parameters: {"secret"=>1969-12-31 19:00:00 -0500}
A patched server raises a Hash::DisallowedType (Disallowed type attribute: "yaml") exception.
I saw the /gigapans/ in the URL and googled for it, thinking it must be a super intelligent panoramic "image sticher"+"image viewer" written in flash - but found this: http://en.wikipedia.org/wiki/Gigapan
My first real programming job involved building web apps using OpenACS - http://openacs.org/. OpenACS was all Tcl executing in AOLServer and used postgres or oracle. It was awesome.
I Learned a lot from "Tcl for Web Nerds" and its companion "SQL for web nerds" (all links listed here: http://openacs.org/doc/ ). Back when I started Tcl, I was more like a emacs-lisp script kiddie. Because Tcl was so easy to learn and because OpenACS was such a great MVC style framework, it didn't take long to master the framework itself and dive into the interesting things that were related more with the architecture of a web-app and not just the syntax of a programming language.
Miguel Sofer had described an algorithm for representing hierarchical data in a RDBMS. What he put forward could be thought of as a different kind of a nested set representation. Whereas the nested-set approach involved keeping track of two numeric values (left & right) for each node in our relational records based tree, Miguel Sofer's algorithm would use the ability to lexically sort a base159 encoded string. This way, tree operations could be implemented via sub-string matching and sorting.
His algorithm was implemented in OpenACS because it allowed an efficient implementation of the OpenACS nodes table. Each URI in OpenACS has a node record associated with it and all these nodes are hierarchical records - http://openacs.org/forums/message-view?message_id=16799
The OpenACS nodes system allows the implementation of a fine grained permissions system which enables a child node to auto-magically inherit the permissions of its parent node - this is, if the child node didn't have any specific permissions set on itself - http://openacs.org/doc/permissions-tediously-explained.html
From what I understand, Linux runs the rover simulator environment - known as RSVP. It consists of a DSL that is used to direct the rover's operations and a visualization environment. This way the ground crew can first plan and test the activities they want the rover to perform in this simulated environment and then upload the action plan to the rover - so overall Linux plays a pretty important part in the the rover tech stack.
Most probably the initial rovers ran VxWorks RTOS, because back then it was the best choice (even now it isn't a bad choice at all) - complex systems are built incrementally.
I recently discovered an old chemistry book that is supposedly banned from publication, but since it's not under any copyright anymore we can download it with breaking any rules : http://openmaterials.org/2010/03/18/banned-the-golden-book-o... -- I am finding it really cool to read and learn from.
I haven't used airbnb but after reading some of the comments here, I looked up the airbnb site to check if they have tools/features which try to address the "I am renting to a total stranger/I am renting a strange place" issue - http://www.airbnb.com/safety#reputation - I guess these tools could be improved/enhanced.
But, just because something doesn't follow an established pattern, doesn't mean its illegal. It would make sense if a community decided to add a "no airbnb" clause to their bylaws/rules - but the govt picking and deciding what is abuse of resources and what is not doesn't sound practical - esp when the resource usage of an airbnb unit is no different when it is rented out versus the owner(s) occupying it themselves.
If there can be things like credit-default-swaps, I don't see why the insurance industry should not come up with instruments for this kind of a market - where there is a market, there must be a way.
For me FB is the proverbial ghost town - because I am no longer interested in the contents of activity feed I get on FB :-p . I am sure my opinions don't matter much, after all, I don't have thousands of friends on either of the two services.
But for whatever its worth, I've started to really like G+ since I've started to follow Linus Torvalds and Stephen Kinsella on G+. I like the drag-drop UI that "Circles" tab/widget implements and I love the posts that Linus shares with the public. I don't know if Linus has/uses FB too, but I don't care.
I think that if Google runs G+ long enough and has cool & intelligent people using/developing it, G+ will not do too bad.
I am from India and I am pretty concerned about terrorism, but I am assuming that the people/businesses who will end up following such rules would most probably be the people who aren't planning any thing nefarious.
Meanwhile, the real bad guys are going to find a way around it - and will the govt of India pay me damages if my private key ended up on piratebay because someone stole it from their servers? Nope, don't think so.
Most Indian's have been brainwashed into accepting flaws/weaknesses in (big)governance, kind of like - "its a feature, not a bug"
==> Is it implied that since the average American doesn't like some work, America is being afforded a chance to uplift "Chinese farmers" and whole bunch of other poor people? Is it?
==> Isn't such a thought ridiculous? Such a thought, I think implies that the global economy is a kind of a neo-socialist+charitable-capitalistic kitchen whose main aim is to feed the poor and in the process fatten some of them more than the others. Is it?
==> I think that the right question to ask is not if - Amazon Can Make A Kindle In the USA? The right question should be - Is the Amazon Kindle manufacturing ecosystem truly balanced? - If not, then in the long run some parts of the ecosystem will be eliminated, so that the ecosystem finds a balance.
==> Different regions have different geographic/social/economic environments and will be better suited for some kind of work than other regions. One can not ignore these facts.
But, does amazon have a real stake in the companies that make the Kindle China/Korea? I think not. Isn't there an imbalance between what these companies gain, in terms of ability, from this ecosystem and what the rest of the ecosystem (Amazon/American) gets back?
I dont think american companies have a stake in the Chinese/Korean companies/economies that they outsource to. In return they give you low cost electronics - in process building the largest reserves of dollars in the world and building the ability to innovate themselves in the long run.
==> There is no point in being crazy nationalist. But I don't understand why a nation with such a huge continent can't find a place where it can build a manufacturing hub that can participate in the global manufacturing industry.
The country has enough people to enable a volunteer military, but for some reason can't find people who can build a manufacturing hub? even if this was the case - haven't immigrants signed up before?
I don't consider myself a "real" assembly programmer. I can, however, try to debug compiled c code via gdb disassemble and not get totally lost.
I managed to pick up this ability after getting to know assembly programming, and the subsequent "higher level manifestations" in C/C++, from Paul Carter's open source ebook: http://www.drpaulcarter.com/pcasm/
When I first downloaded this book in 2002, I was fairly comfortable with the linux command line, gcc and emacs, but I knew nothing about assembly and computer architecture (registers/interrupts etc).
Whereas other books on assembly were somehow tied to DOS, this was a free book that wasn't tied to any OS and was easy to understand.
Here in India, I was able to get an Android smart phone for half the price of an iPhone. I can also build Android apps on my Debian Linux machine without incurring any additional costs.
The fact that the devices cost lesser(even before the phone company subsidizes it) and yet have GPS and an accelerometer enables me to at least attempt certain kinds of applications that target the mass market here in India.
Also, the ability to read the source code allows me to learn about a smartphone operating system in the same way I got know about a PC operating system by reading Linux's source code.
I would never want Android to be like OLPC. Android is more like a free market. OLPC was charity.
Apple has every right to protect its intellectual property. I think it is equally important for Americans to debate about, and review, the American patent system (where required).
Overall, if HTC can pay royalties to MS, then I guess they can do the same with Apple.
Since large orders are filled by different markets, anyone who has studied the mechanisms via which these orders are full-filled can theoretically arrive at a strategy that might be profitable. Overtime, more and more people will learn these things and it will no longer be a profitable strategy to implement - this is sort of like the "January Effect" described in the book named intelligent investor.
I don't understand why HFT has to be blamed for a difference in prices across multiple markets. I read somewhere that REGNMS caused market fragmentation and HFT traders spend time studying the current markets and identify inefficiencies that can be used to make profitable trades.
This Reuters article is like an advertisement for the IEX trading platform. IEX figured out a certain way to beat the other algorithms and they told Reuters about it. Now that everyone knows it, I think, pretty soon other algorithm developers will modify their implementations.
Overall, I think that HFT is basically algorithmic trading, but which needs more investment (for renting/buying server/connectivity) and more time/interest (for studying and understanding the order placement/fulfilment mechanisms involved).