▁ ▁Current ▁through ▁the ▁ 2 0 1 5 ▁US ▁Open ▁ ▁Record ▁against ▁top ▁ 1 0 ▁players ▁ ▁Pen net ta ' s ▁match ▁record ▁against ▁players ▁who ▁have ▁been ▁ranked ▁in ▁the ▁top ▁ 1 0 ▁ ▁No . ▁ 1 ▁wins ▁ ▁Top ▁ 1 0 ▁wins ▁ ▁External ▁links ▁ ▁Un o fficial ▁website ▁▁▁▁▁▁▁ ▁Category : T ennis ▁career ▁statistics <0x0A> </s> ▁Hend rik ▁Jan ▁Ma arten ▁" H enk " ▁Bos ▁( born ▁ 1 7 ▁July ▁ 1 9 4 0 , ▁En sch ede ) ▁is ▁a ▁Dutch ▁historian ▁of ▁mathematics . ▁ ▁Career ▁Hend rik ▁was ▁a ▁student ▁of ▁Hans ▁Fre udent hal ▁and ▁Jer ome ▁Rav etz ▁at ▁U tre cht ▁University ▁and ▁in ▁ 1 9 7 3 ▁wrote ▁a ▁th esis ▁" D iffer entials , ▁higher ▁order ▁differential s , ▁and ▁the ▁derivative ▁in ▁Lie bn itz ian ▁calculus " ▁for ▁his ▁doctor ate . ▁▁ ▁Bos ▁worked ▁at ▁U tre cht ▁University ▁for ▁most ▁of ▁his ▁career . ▁In ▁ 1 9 8 5 ▁he ▁became ▁professor ▁of ▁history ▁of ▁mathematics . ▁ ▁He ▁took ▁an ▁interest ▁in ▁the ▁tract rix ▁as ▁a ▁mathematical ▁stim ulus . ▁ ▁Bos ▁retired ▁in ▁ 2 0 0 5 . ▁ ▁Since ▁his ▁ret irement ▁he ▁has ▁been ▁honor ary ▁professor ▁of ▁the ▁history ▁of ▁mathematics ▁at ▁the ▁Fac ulty ▁of ▁Science ▁at ▁the ▁University ▁of ▁A ar hus . ▁He ▁is ▁married ▁to ▁K irst i ▁Anders en . ▁