About Operating Systems concepts

hi all
i have question about concurrency processing in operating systems concepts
suppose that we have two process A,B that running concurrently in a computer.
we have the following algorithm. (this is for A , for B replace a to b)

Code:

---

:retry
flag[a]=false;
if (flag[b] != false ) goto retry;
flag[a]=true;
if (flag[b] != false ) goto retry;
// critical section
flag[a]=false;

---

we know each ideal algorithm for critical section accessing must have three constraints : 1.mutual exclusion , 2.progress , 3.bounded waiting
my question is: for the above algorithm which of these constrain(s) have?

best regards...

Is this some kind of school task?

yes , this is a university assignment for course OS
i think this algorithm has not "Progress" constraint, but not sure!
by this algorithm the "Mutual Exclusion" has been met.
what about Progress cons. ??
thanks Mr Wysota

I'm sorry, we're not allowed to solve school tasks.

please suppose this is not a school task ! :D
just tell me this algorithm satisfy "Progress" or not ?

thanks Mr Wysota

You may also check the video to get basic idea of semaphore and shared resource.

https://www.youtube.com/watch?v=VQFJQJGmixM