My daily readings 05/04/2009
Inverted index – Wikipedia, the free encyclopedia
The inverted index data structure is a central component of a typical search engine indexing algorithm. A goal of a search engine implementation is to optimize the speed of the query: find the documents where word X occurs. Once a forward index is developed, which stores lists of words per document, it is next inverted to develop an inverted index. Querying the forward index would require sequential iteration through each document and to each word to verify a matching document. The time, memory, and processing resources to perform such a query are not always technically realistic. Instead of listing the words per document in the forward index, the inverted index data structure is developed which lists the documents per word.
With the inverted index created, the query can now be resolved by jumping to the word id (via random access) in the inverted index. Random access is generally regarded as being faster than sequential access.
In pre-computer times, concordances to important books were manually assembled. These were effectively inverted indexes with a small amount of accompanying commentary, that required a tremendous amount of effort to produce.
Apple’s iPhone app store appeals to small businesses – May. 1, 2009
The availability of such a wide variety of small-business-oriented apps prompted Jason Miller, owner of San Diego construction and design company Wise Man, to switch his firm to iPhones from BlackBerrys about eight months ago.
His managers travel among construction sites, and they use an iPhone app called Air Sharing to trade blueprints and time-tracking software TSheets to monitor workers’ hours. The GasBag app helps the team find the lowest fuel prices in San Diego County. Miller, who says he has spent about $100 on iPhone software, personally does about 30% of his “computing” on the iPhone, the rest on an office desktop.
Posted from Diigo. The rest of my favorite links are here.