▁him ▁from ▁further ▁military ▁service ▁during ▁World ▁War ▁II . ▁ ▁After ▁the ▁war ▁P esch l ▁became ▁the ▁director ▁of ▁the ▁Institute ▁of ▁Mathemat ics ▁in ▁Bonn , ▁and ▁in ▁ 1 9 4 8 ▁he ▁became ▁a ▁full ▁professor ▁there . ▁He ▁promoted ▁applied ▁mathematics ▁and ▁established ▁the ▁Institute ▁for ▁Inst rument al ▁Mathemat ics ▁in ▁Bonn ▁which ▁evol ved ▁into ▁the ▁Society ▁for ▁Mathemat ics ▁and ▁Data ▁Process ing . ▁He ▁led ▁the ▁Society ▁with ▁Hein z ▁Un ger ▁from ▁ 1 9 6 9 ▁to ▁ 1 9 7 4 . ▁ ▁Work ▁▁ ▁Ernst ▁P esch l ' s ▁main ▁areas ▁of ▁research ▁were ▁geometric ▁complex ▁analysis , ▁partial ▁differential ▁equations , ▁and ▁the ▁theory ▁of ▁functions ▁of ▁several ▁complex ▁variables . ▁ ▁P esch l ▁was ▁the ▁doctor al ▁ad visor ▁of ▁Cla us ▁Müller , ▁Fried helm ▁Er we , ▁Karl ▁Wilhelm ▁B auer , ▁Bern hard ▁K orte , ▁Ste phan ▁Rus che we y h , ▁and ▁Karl - Jo achim ▁W irth s , ▁among ▁others . ▁ ▁P esch l ▁received ▁an ▁honor ary ▁doctor ate ▁from ▁the ▁University ▁of ▁Toul ouse ▁in ▁ 1 9 6 9 ▁and ▁another ▁honor ary ▁doctor ate ▁from ▁the ▁University ▁of ▁Gra z ▁in ▁ 1 9 8 2 . ▁For ▁his ▁fruit ful ▁collaboration ▁with ▁French ▁mathemat icians , ▁the ▁French ▁government ▁awarded ▁him ▁an ▁Offic ier ▁des ▁Pal mes ▁Ac adém iques ▁in ▁ 1 9 7 5 . ▁ ▁P esch l