Proof of correctness for algorithms

Pencast for the course Reasoning & Logic offered at Delft University of Technology.

Accompanies the open textbook: Delftse Foundations of Computation.

[cosminanton]

Can you reupload the videos with the sound a little bit higher?

[Soulmiddes]

cant even see what you are writing lol

[Boneplayer]

Sure, I would have loved to see values for the variables, or at least seen where ‘a’ originates. But I did in fact learn how to make a simple proof.

[seekanddestroyNL]

This algorithm will only work for m>=0 and m would have to be an integer. So this algorithm does not produce m*a in the general case

[davidrahabi]

Very clear explanation thank you for the help!

[rahulankamreddi]

in algorithm r=r+a how come it changed to r=i.a ?

[jbipmni]

how to proof correctness of this algorithm:
function increment(y)
comment Return y + 1, where y in N
x := 0; c:= 1; d:= 1;
while (y > 0) V (c > 0) do
a :=y mod 2;
if a XOR c then x=x+d;
c:= a AND c;
d:= 2d; y := [y/2] :
return(x)