jm + bst   4

MaxMind DB File Format Specification
An interesting data structure format -- 'the MaxMind DB file format is a database format that maps IPv4 and IPv6 addresses to data records using an efficient binary search tree.'
maxmind  databases  storage  ipv4  ipv6  addresses  bst  binary-search-trees  trees  data-structures 
7 weeks ago by jm
Communications data errors: UK police incriminating the wrong people due to data retention system screwups
It seems there have been 34 with serious consequences since 2008. Causes include:
- Omission of an underscore when transcribing an e-mail address led to the wrong subscriber information being provided and a search warrant being executed at the premises of an individual unconnected with the investigation.

- A CSP's data warehouse system change affected how GMT and British Summer Time were treated. This was not communicated to staff using the data retention disclosure system. This led to a one hour error in subscriber information disclosed in relation to IP address usage. Of 98 potential disclosure errors identified, 94 were in fact incorrect and four returned the same results when re-run. Of the 94 incorrect disclosures, in three cases a search warrant was executed at premises relating to individuals unconnected with the investigation (and one individual was arrested).

- Due to a technical fault causing a time zone conversion to be out by seven hours, a CSP voluntarily disclosed an incorrect IP address to a public authority.  That led to a search warrant being executed at premises relating to individuals unconnected with the investigation.


In other words, timezones largely screw up everything, yet again.
timezones  uk  law  data-retention  errors  bst 
march 2017 by jm
US immigration asking tech interview trivia questions now
what the absolute fuck. Celestine Omin on Twitter: "I was just asked to balance a Binary Search Tree by JFK's airport immigration. Welcome to America."
twitter  celestine-omin  us-politics  immigration  tests  interviews  bst  trees  data-structures  algorithms 
february 2017 by jm
Lectures in Advanced Data Structures (6.851)
Good lecture notes on the current state of the art in data structure research.
Data structures play a central role in modern computer science. You interact with data structures even more often than with algorithms (think Google, your mail server, and even your network routers). In addition, data structures are essential building blocks in obtaining efficient algorithms. This course covers major results and current directions of research in data structures:

TIME TRAVEL We can remember the past efficiently (a technique called persistence), but in general it's difficult to change the past and see the outcomes on the present (retroactivity). So alas, Back To The Future isn't really possible.
GEOMETRY When data has more than one dimension (e.g. maps, database tables).
DYNAMIC OPTIMALITY Is there one binary search tree that's as good as all others? We still don't know, but we're close.
MEMORY HIERARCHY Real computers have multiple levels of caches. We can optimize the number of cache misses, often without even knowing the size of the cache.
HASHING Hashing is the most used data structure in computer science. And it's still an active area of research.
INTEGERS Logarithmic time is too easy. By careful analysis of the information you're dealing with, you can often reduce the operation times substantially, sometimes even to constant. We will also cover lower bounds that illustrate when this is not possible.
DYNAMIC GRAPHS A network link went down, or you just added or deleted a friend in a social network. We can still maintain essential information about the connectivity as it changes.
STRINGS Searching for phrases in giant text (think Google or DNA).
SUCCINCT Most “linear size” data structures you know are much larger than they need to be, often by an order of magnitude. Some data structures require almost no space beyond the raw data but are still fast (think heaps, but much cooler).


(via Tim Freeman)
data-structures  lectures  mit  video  data  algorithms  coding  csail  strings  integers  hashing  sorting  bst  memory 
april 2013 by jm

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