He provided the first comprehensive modern summary of Stoic logic, as well as incorporating Aristotelian syllogisms into a de
He provided the first comprehensive modern summary of Stoic logic, as well as incorporating Aristotelian syllogisms into a deductive system.  He also obtained several important results in sentimental calculii, and posited the existence of a third truth-value, "possible," in his 1918 paper on Aristotle's notion of future possibility.  FTP, name this Polish philosopher, the best known of the "Warsaw School" of logicians.
He provided the first comprehensive modern summary of Stoic logic, as well as incorporating Aristotelian syllogisms into a deductive system.  
Jan Lukasiewicz (LOOK-as-eew-itz)