From The Washington Post

On Friday, Yahoo added to its claims of infringement against Facebook, in addition to denying that it violates any of the patents named in the social network’s countersuit.

The additional claims involve the “System and Method to Determine Validity of and Interaction on a Network” and the “System and Method Allowing Advertisers to Manage Search Listings in Pay for Placement Search System Using Grouping,” which the company says is violated by Facebook Ads.

In the filing, Yahoo also hits out at Facebook for asserting patents in-suit that it purchased from other companies — notable, as Facebook recently purchased 650 patents from Microsoft. The patents, originally held by AOL, were viewed as a way for the social network to better defend itself against infringement claims.

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