Visitor: Number Theory Group Visited York to give Number Theory Study Group seminar entitled 'The Goldston-Pintz-Yildirim theorem: L1'. 1 May 2008 Visited York to give Number Theory Study Group seminar entitled 'The Goldston-Pintz-Yildirim theorem: L2'. 6 May 2008 Visited York to give Number Theory Study Group seminar entitled 'The Goldston-Pintz-Yildirim theorem: L3'. 8 May 2008 Visited York to give Number Theory Study Group seminar entitled 'The Goldston-Pintz-Yildirim theorem: L4'. 12 May 2008 Visited York to give Number Theory Study Group seminar entitled 'The Goldston-Pintz-Yildirim theorem: L5'. 15 May 2008