qu enc ourt , ▁and ▁É cole ▁des ▁Haut es ▁Ét udes ▁en ▁Sciences ▁Social es . ▁ ▁During ▁his ▁time ▁in ▁Water lo o , ▁Cra po ▁became ▁a ▁Canadian ▁citiz en . ▁ ▁Cra po ▁is ▁known ▁for ▁his ▁early ▁work ▁in ▁mat roid ▁theory , ▁and ▁for ▁related ▁work ▁in ▁lattice ▁theory . ▁ ▁He ▁introduced ▁the ▁beta ▁invariant ▁of ▁a ▁mat roid , ▁and ▁published ▁the ▁first ▁paper ▁on ▁the ▁T ut te ▁polynomial ▁( though ▁T ut te ▁had ▁already ▁defined ▁an ▁equivalent ▁polynomial ▁in ▁his ▁th esis ). ▁ ▁T ogether ▁with ▁Gian - Car lo ▁R ota , ▁Cra po ▁wrote ▁the ▁first ▁book ▁on ▁mat roid ▁theory . ▁ ▁He ▁is ▁also ▁known ▁for ▁Cra po ' s ▁Com plementation ▁Theorem ▁in ▁pos et ▁M ö b ius ▁In version . ▁ ▁Cra po ▁wrote ▁ 6 5 ▁mathematical ▁publications ▁during ▁his ▁career . ▁ ▁Upon ▁his ▁ret irement , ▁Cra po ▁moved ▁to ▁the ▁south ▁of ▁France . ▁ ▁He ▁continued ▁some ▁mathematical ▁activity , ▁and ▁hosted ▁several ▁small ▁con ferences ▁at ▁his ▁house ▁there . ▁ ▁He ▁died ▁on ▁September ▁ 3 , ▁ 2 0 1 9 . ▁ ▁Awards ▁and ▁hon ors ▁ ▁A ▁special ▁ 1 9 9 9 ▁issue ▁of ▁the ▁journal ▁Adv ances ▁in ▁App lied ▁Mathemat ics ▁was ▁dedicated ▁to ▁Cra po ▁on ▁the ▁occasion ▁of ▁his ▁ 6 7 th ▁birth day . ▁ ▁Personal ▁life ▁ ▁Cra po ▁was ▁a ▁patron ▁of ▁the ▁arts .