Ex-3.45

There will be a deadlock. Here is why...

(serialized-exchange account1 account2)
...
...
(serializer1 (serializer2 exchange) account1 account2)
...
Notice, call to exchange is serialized in both the
serializers, so they won't let any other serialized
procedure run unless this call completes.

exchange makes following call..
(- (account1 'balance) (account2 'balance))
...
(account1 'balance)
This is a serialized call with the given code in the 
problem and will be blocked because serializer1 is still 
waiting for exchange call to complete.