Prof. Charles Antony Richard Hoare

Tony Hoare

Born in Colombo (Sri Lanka)

British parents

Oxford (England)

University of Oxford:

Hoare studied:• Philosophy • Latin and Greek• Bacherol Degree in

1946• Extra year: Statistics

Moscow (Russia)

Hoare studied:• Russian (in the Royal

Navy) • Statistics• a programming

course

University State of Moscow

- machine translation of languages - probability theory

Back to England (London) in 1960

Elliot Brothers (a small scientific computer manufacturer)

First task: Elliot 803• Implementation of the method for internal sorting

invented by Shell• Hoare believed he had a faster method

Elliot 503 (the companie´s next computer) Goal: Design the language• Course on the language Angol 60 (in Brighton - England ) • First contact with recursive procedures• Wrote the procedure of Quicksort

New direction: Implementation of Algol 60

(Hoare was invited to the group with responsibility for maintenance and development of Algol.)

Back to Elliot Brothers...

• Hoare was leading a team of 15 programmers

( task: Implementation of an operating system to the

Elliot 503 computer)

• Promoted to Chief Engineer

( task: responsible for development and design of the company´s products)

Hoare left the industrywhat was the reason?

- Hoare proposed once that a programming language definition should be formalized as a set of axioms instead of a just a functional notation.

- But he did not see how actually to do it.

Long Term research?

Research at Queen´s University (Belfast)(1968-1977)

- Theory of Programming and Languages

Hoare Logic

Instantiation axiom

{p[t/y]} y:=t {p}

For example:

{y+5=10} y:=y+5 {y=10}

{y+y<z} x:=y {x+y<z}

{2*(y+5)>20} y:=2*(y+5) {y>20}

Composition rule

{p} S1 {r} {r} S2 {q}________________________________________________________________________

{p} S1;S2 {q}

For example: if the antecedents are

1. {x+1 = y+2} x := x+1 {x=y+2}

2. {x = y+2} y := y+2 {x=y}

Then the consequent is

{x+1 = y+2} x := x+1; y := y+2 {x=y}

While rule

{p/\e} S {p}________________________________________________________________________

{p} while e do S od {p/\¬e}

Assertions example

{x>=0 /\ y>=0} a:=0; b:=x;while b>=y do b:=b-y; a:=a+1od.{x=a*y+b/\b>=0/\b<y}

Back to Oxford University (1977)

Continuation of the research leads to:

• CSP (Communicating Sequential Processes)

1980 – Receives Turing Award

For his fundamental contributions to the definition and design of

programming languages

Back to Industry (1999)

Senior researcher with Microsoft Research in Cambridge