Bangalore: Yahoo last month went all hunky dory about Facebook stealing its ideas, and now Yahoo is facing music on its own grounds . In a symmetrical fashion to what Yahoo did, Facebook has filed a counter-suit claiming patent infringement on 10 different patents including two that list CEO Mark Zuckerberg as the inventor as reported by Business Insider.

"From the outset, we said we would defend ourselves vigorously against Yahoo's lawsuit, and today we filed our answer as well as counter-claims against Yahoo for infringing ten of Facebook's patents," Ted Ullyot, Facebook's general counsel, as stated by Mashable.  "While we are asserting patent claims of our own, we do so in response to Yahoo's short-sighted decision to attack one of its partners and prioritize litigation over innovation."

The accusations are "without merit and nothing more than a cynical attempt to distract from the weakness of its defense." Is what is believed Yahoo has said in a statement according to NY News & Features.

The epic fight which is gearing steam between the two tech giants might prove to be a major blow to Yahoo, if it loses as it is already struggling with innovation phase and has turned towards patent licensing.

So the 10 patents Facebook is using as weapons to scare away Yahoo, so that it drops the suit against them are as below. Abstract and details are taken from Google and ZDnet.

1. The system of generating a personalized story on a social network based on the user’s actions as other actions of the users. Facebook claims Yahoo! Flickr features like Photostream, Recent Activity and Groups Activity infringe on this patent.

U.S. Patent No: 7,827,208

“Generating a feed of stories personalized for members of a social network”

Filed on:  August 11, 2006

Granted: November 2, 2010

Abstract: Systems and methods for generating dynamic relationship-based content personalized for members of a web-based social network are provided. At least one action of one or more members of a web-based social network is associated with relationship data for the one or more members to produce consolidated data. One or more elements associated with the consolidated data is identified and used to aggregate the consolidated data. Further exemplary methods comprise weighting by affinity the aggregated consolidated data to generate dynamic relationship-based content personalized for the members of the web-based social network.