1. Page 75 of the second paper by Guttag, Horowitz and Musser presents an implementation of a
queue using a circular list, and starts to prove that the implementation satisfies the definition of the
Queue type by proving two of the a
for Distributed Systems
Course notes by
and the LOTOS group
University of Ottawa
School of Information Technology and Engineering
Telecommunications Software Engineering Research Group
please read course descr
CSI 5109 Assignment 4
1. By constructing the refusal trees of the two behaviour expressions below, show that conformance is not a symmetric relation.
A = a; b; stop  c; stop
B = i; a; stop  b; c; stop
Assignment 3 - CSI5109
A disk drive is to be shared among two concurrent users. However, they are not allowed to
use it at the same time. In the following system, the OS uses a semaphore to ensure that only
one user at a time can perform a read followe
DNS is delegated hierarchically by having. e.g. the root nodes tell
resolvers which servers to quer}.r for “.con1“_. and so on, until the client’s
query can he answe
Main LOTOS operators
(operators are used to combine actions and behavior expressions
into more complex b.ex.)
(let a, a1, a2,. be actions, and B, B1, B2. be behavior expressions).
a; B: the action prefix operator ; means that
More LOTOS Operators
TERMINATION IN LOTOS
UNSUCCESSFUL TERMINATION: STOP
off_hook ; tone ; dial ; connect ; breakdown ; stop
SUCCESSFUL TERMINATION: EXIT
off_hook ; tone ; dial ; connect ; exit
Unsuccessful termination can be specified either explicitly b
Much of this class is dedicated to the discussion of
C.A.Visser, G. Scollo, M.v. Sinderen, E. Brinksma
Specification Styles in Distributed System Design and
Theoretical Computer Science 89 (1991) 179-206
1. (20 points) Grading is +2 points for a correct answer and El points for either blank or
incorrect. In other words: at the end of the exam. if you don't know the answer to any
of these. guess because you'll get more points in expectation. If
ENABLING WITH VALUE TRANSMISSION
(See in B&B tutorial discussion re: exit + functionality).
Upon termination, a process can "exit" a set of values.
These can be passed on to an enabled process.
process P[a] : exit(nat, bool):=
a ? x:nat ? y:nat;
FORMAL CONCEPTS OF
VIEWS OF IMPLEMENTATION
(Brinksma, Scollo, van Steenbergen)
implementation as a synonym of the real/physical system that
is the subject of conformance requirements and conformance
testing [view not
Equivalence Relations are a very important
aspect of algebraic specification techniques.
In other techniques (such as EFSM-based) we
dont have such extensive theory of equivalence.
Although proving equivalence of real-life specs
Equality and Expansion
THE IDEA OF THE EXPANSION LAWS
Let us see a behavior expression as a syntactic tree having
operators as nodes:
The expansion laws allow to transform this behavior
expression into another on
This class and the next ones try to give a pragmatic introduction
to the subject of recursive programs and Abstract Data Types.
These are subjects on which whole courses are taught. The treatment here is quick and