Hide Notes 

Slide 1: 1 Władysław M. Turski
Slide 2: It Was Fun While It Lasted 2 Władysław M. Turski
Slide 3: It Wasn't Much Fun 1959, Moscow (USSR), M.Sc. Thesis I was a computer 3 Władysław M. Turski
Slide 4: It Was Fun 1960, Manchester (UK), Mercury When love prevails Logic fails So the computer Was made neuter 4 Władysław M. Turski
Slide 5: It Was Fun Computing meteor stream orbits 5 Władysław M. Turski
Slide 6: It Was Fun Running simulations of meteor swarm’s evolution 6 Władysław M. Turski
Slide 7: It Was a Mistake I thought the computer was for computing (Just as Aristotle thought brain was for cooling blood) 7 Władysław M. Turski
Slide 8: But it took me long time to see the light First I thought computers were too difficult to program 8 Władysław M. Turski
Slide 9: But it took me long time to see the light So I wrote compilers KLIPA, ALGOL-60 9 Władysław M. Turski
Slide 10: But it took me long time to see the light Then I thought running programs on computers was too messy 10 Władysław M. Turski
Slide 11: But it took me long time to see the light So I wrote an operating system SODA 11 Władysław M. Turski
Slide 12: But it took me long time to see the light Then I thought something was amiss with the data 12 Władysław M. Turski
Slide 13: But it took me long time to see the light So I played with data structures 13 Władysław M. Turski
Slide 14: And I’ve sinned For five long years I worked in the industry. Directing the transfer of OS/360 to Polish-made RIAD computers. 14 Władysław M. Turski
Slide 15: Much later (1983, Dublin) Responding to an invited paper I said: Fred Brooks is a hard act to follow: I know, I’ve lifted the OS/360 ! 15 Władysław M. Turski
Slide 16: Then I thought I saw the light Computer is for executing programs! 16 Władysław M. Turski
Slide 17: Programming methodology Structured programming (programming structures) GOTO considered harmful 17 Władysław M. Turski
Slide 18: Programming methodology Step-wise refinement Correctness 18 Władysław M. Turski
Slide 19: Programming methodology Correctness, yes but what does it mean? With respect to ... 19 Władysław M. Turski
Slide 20: Programming methodology Correctness wrt formal specification - „faultily faultless” - clear, but useless 20 Władysław M. Turski
Slide 21: Programming methodology Specs ? Correctness Ill-defined relationship Reality 21 Program Władysław M. Turski
Slide 22: Programming methodology Theory Satisfaction Satisfaction Well-defined relationship Model 22 Model Władysław M. Turski
Slide 23: I was sure I saw the light It all reduces to theories. A good theory leads to good programs and satisfied customers. A poor theory hinders construction of good programs and makes customers weep. 23 Władysław M. Turski
Slide 24: I was sure I saw the light Build theories of small domains, make program-models for them, then combine theories and programs shall jell together! 24 Władysław M. Turski
Slide 25: I was sure I saw the light But it ain’t necessarily so! • combining theories is difficult (and not always possible) • combining implementations is (nearly always) messy and often dangerous 25 Władysław M. Turski
Slide 26: I was sure I saw the light I thought that perhaps combinig little actions into larger systems should be done entirely without any notion of „time”, i.e even without any predetermined notion of „follows”. 26 Władysław M. Turski
Slide 27: I was sure I saw the light Thus the concept of doubly guarded command ( front action rear ) was born and (partially) explored 27 Władysław M. Turski
Slide 28: But while I followed the light The world was changing became the soup du jour 28 Władysław M. Turski
Slide 29: In the new brave world Computers, becoming ever more numerous (and physically smaller), disappear behind services they provide. 29 Władysław M. Turski
Slide 30: In the new brave world Computation has to be correct. Service has to be dependable. 30 Władysław M. Turski
Slide 31: In the new brave world The mathematical, strict criterion of correctness is being replaced by a behavioural, loose criterion of dependability. 31 Władysław M. Turski
Slide 32: In the new brave world All actors (people, machines and systems thereof) occasionally malfunction. This is not only accepted, but also expected. 32 Władysław M. Turski
Slide 33: In the new brave world No-one really complains that Windows is prone to crash, only that it crashes at an inopportune moment. 33 Władysław M. Turski
Slide 34: In the new brave world Like no-one complains that tires occasionally go flat, only that it happens when we are particularly short of time. 34 Władysław M. Turski
Slide 35: In the new brave world No-one is to blame and the guilt is subtly shifted to the „user”: If I only didn’t drive there, if I only didn’t press these two keys together! Or was it three? 35 Władysław M. Turski
Slide 36: In the new brave world Every hour more users than babies are born. Each user soon becomes an expert at their specific fingering. Such an expertise quickly becomes an article of faith and an academic discipline. 36 Władysław M. Turski
Slide 37: In the new brave world Particular fingerings turned articles of faith cum academic disciplines are invested. 37 Władysław M. Turski
Slide 38: An aside, from Webster’s: invest - to array in the symbols of office and honor - to furnish with power or authority - to surround with troops or ships so as to prevent escape or entry - to commit money in order to earn a financial return 38 Władysław M. Turski
Slide 39: In the new brave world In the ecumenical primordial ocean of Internet, growth is primarily by accretion of external grime. Reason is yet to be born: while no-one convinces, many try to catch. 39 Władysław M. Turski
Slide 40: In the new brave world Correctness, rigour, mathematics of computing is pushed into an ever smaller and darker corner labelled „special concerns”. 40 Władysław M. Turski
Slide 41: I have the feeling that Having witnessed the birth of computing science, I am witnessing its demise. 41 Władysław M. Turski
Slide 42: While it lasted It certainly was fun! 42 Władysław M. Turski
Slide 43: ? 43 Władysław M. Turski