1. A Dynamic Deontic Logic over Synchronous Actions
a.k.a. CL: A Logic for Contracts
Cristian Prisacariu
Precise Modeling and Analysis group (PMA),
University of Oslo
at
PhD Defence
at Institute of Informatics, University of Oslo
8th December 2010, Oslo, Norway.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 1 / 69
2. For Bob, the carpenter
What is this research/talk about?
Contracts, legal contracts – like the ones signed with TV company or
when buying a car – complicated contracts, like the ones that humans
cannot understand, but only lawyers can.
Computers and how to make them understand contracts, reason about
contracts, and answer questions coming from humans about a
contract. (Maybe could also help lawyers with their work.)
Logic is the thing that the computer needs to do such tasks.
This thesis investigates the Contracts Logic needed by the computer to be
able to do useful tasks with contracts. The thesis concentrates in particular
on two such tasks: model checking and runtime monitoring. (Stay alert and
later you will understand what these are.)
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 2 / 69
3. Bob asks: “You like lawyers so much?”
“Or you don’t like lawyers but like poor people like me?”
I like Computer Science, the Internet, and all the electronic commerce
that you use on your phone. I like programming and electronic
intelligent agents.
In many fields of CS one finds different forms of contracts: electronic
contracts, software contracts, behavioral interfaces, agent norms, etc.
Legal contracts are more complex than all these. If I can do something
with the legal contracts, then with almost no effort I can do the same
thing for Computer Science contracts.
Developing a logic for legal contracts may help both lawyers as well as you
or my wife, and at the same time it would reach the goal of the COSoDIS
project (where I was payed from) which wanted to use contracts to regulate
sevice exchage, like in web services or component-based systems.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 3 / 69
5. The Honeymoon Example
You planned to go one week honey-
moon with your spouse, tenting in
the mountains. To get close to this
far remote and beautiful place you
need to rent a car.
But, of course, they give you a con-
tract to sign first.
Because it is a rather thick contract
and you like to read before signing
anything ... you take it home.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 4 / 69
6. The Honeymoon Example
But it is somehow difficult for your
limited intellect to decipherer what
is written in the contract. You do
not even understand the English lan-
guage in many places; you need to
do all sorts of math calculations; to
keep track of all those definitions; to
constantly check the dates in the cal-
endar ...
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 5 / 69
7. The Honeymoon Example
But it is somehow difficult for your
limited intellect to decipherer what
is written in the contract. You do
not even understand the English lan-
guage in many places; you need to
do all sorts of math calculations; to
keep track of all those definitions; to
constantly check the dates in the cal-
endar ...
So you ask help from your spouse, ...
maybe some friends...
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 5 / 69
8. The Honeymoon Example
But it is somehow difficult for your
limited intellect to decipherer what
is written in the contract. You do
not even understand the English lan-
guage in many places; you need to
do all sorts of math calculations; to
keep track of all those definitions; to
constantly check the dates in the cal-
endar ...
So you ask help from your spouse, ...
maybe some friends...
Until you end up at a lawyer.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 5 / 69
10. The Honeymoon Example
⇐ What do you want from this contract?
⇒ I don’t know!
⇐ I tell you what I did with other clients.
You want, for example:
Not to return the car before even
taking it out of the shop.
Not to have to do a full check-up of
the car before returning it.
It also says in this contract that You
have, upon handing in the car, to
also hand in your spouse or a kidny.
⇒ NO!
⇐ Maybe you would like the car to have
Full tank of gasoline; not Empty.
⇒ Yes!
...
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 7 / 69
14. The Honeymoon Example
Finally you sign and get a car.
Now you/spouse are very careful what
you do so to not break the contract.
But how do you know which actions
are OK? Do you read the contract
each time?
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 10 / 69
15. The Honeymoon Example
Finally you sign and get a car.
Now you/spouse are very careful what
you do so to not break the contract.
But how do you know which actions
are OK? Do you read the contract
each time?
Can you play music in car?
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 10 / 69
16. The Honeymoon Example
Finally you sign and get a car.
Now you/spouse are very careful what
you do so to not break the contract.
But how do you know which actions
are OK? Do you read the contract
each time?
Can you play music in car?
Can you drive the car outside city
area?
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 10 / 69
17. The Honeymoon Example
Finally you sign and get a car.
Now you/spouse are very careful what
you do so to not break the contract.
But how do you know which actions
are OK? Do you read the contract
each time?
Can you play music in car?
Can you drive the car outside city
area?
Can you at least blow your nose?
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 10 / 69
18. What does the example try to show?
Contracts need some higher power to understand them.
– maybe computers can do the job...
Certain predefined properties need to be checked against a contract.
– this is called model-checking in the world of logic and CS
Contracts may require negotiation.
– hope for automated form of negotiation of electronic contracts
After signing the contract, monitoring one’s actions may be useful to
ensure that these do not breach the contract.
– run-time monitoring of the actions governed by the contract
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 11 / 69
19. The big picture – The grand challange.
or What Gerardo always wanted?
decidabilitycomplex
NLP
English
text
Model−check prop.
on CL spec.
Automatic
negotiation
on CL specs.
fast det. alg.
push−button
run−time
monitoring
of CL specs.
CL
contract
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 12 / 69
20. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
21. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
22. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
23. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
24. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
25. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
26. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
27. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
28. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
29. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
30. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
31. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
32. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
33. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
34. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
35. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
36. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
37. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
38. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
39. What are the difficulties and the challanges?
or Why the honeymoon was a disaster?
Example
1 The Client shall not:
1 supply false information to the Client Relations Department of the Provider.
2 Whenever the Internet Traffic is high then the Client must pay [price] immediately, or
delay the payment and notify the Provider of the delayed payment.
3 If the Client delays the payment as stipulated in 2, after notification he must immediately
lower the Internet traffic to the normal level, and must pay later twice (2 ∗ [price]).
4 If the Client does not lower the Internet traffic immediately, then the Client will have to
pay 3 ∗ [price].
5 The Client shall, as soon as the Internet Service becomes operative, submit within seven
(7) days the Personal Data Form from his account on the Provider’s web page to the
Client Relations Department of the Provider.
6 Provider may, at its sole discretion, without notice or giving any reason or incurring any
liability for doing so:
1 Suspend Internet Services immediately if Client is in breach of Clause 1;
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 13 / 69
40. Too complicated
1 Propositional notions: statements, implications, conjunctions,
disjunctions (ANDs and ORs)
2 Temporal notions: eventualities, persistence, next step
3 Normative notions: obligations, permissions, prohibitions, powers,
reparations (CTDs, CTPs), governing law
4 Actions; a lot of actions
1 simple actions
2 complicated actions: involving the parties of the contract as subjects
performing the actions; choices of actions, sequences of actions,
actions done at the same time, repetitions
5 Quantities: prices, amounts, (predefined constants or names)
6 Time: durations, deadlines, time stamps
Add: decidability requirements, paradoxes, various properties.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 14 / 69
41. Did I solve it all?
or What did I (try to) solve?
1 Propositional notions: statements, implications, conjunctions,
disjunctions (ANDs and ORs)
2 Temporal notions: eventualities, persistence, next step
3 Normative notions: obligations, permissions, prohibitions,
powers, reparations (CTDs, CTPs), governing law
4 Actions; a lot of actions
1 simple actions
2 complicated actions: involving the parties of the contract as subjects
performing the actions; choices of actions, sequences of actions,
actions done at the same time, repetitions
5 Quantities: prices, amounts, (predefined constants or names)
6 Time: durations, deadlines, time stamps
Add: decidability requirements, paradoxes, various properties.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 15 / 69
42. Where am I in the big picture?
decidabilitycomplex
NLP
English
text
Model−check prop.
on CL spec.
Automatic
negotiation
on CL specs.
fast det. alg.
push−button
run−time
monitoring
of CL specs.
CL
contract
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 16 / 69
43. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
C := φ | OC(α) | P(α) | FC(α) | C → C | [δ]C | ⊥
α := a | 0 | 1 | α×α | α · α | α + α
δ := a | 0 | 1 | δ×δ | δ · δ | δ + δ | δ∗ | ϕ?
ϕ := φ | 0 | 1 | ϕ ∨ ϕ | ϕ ∧ ϕ | ¬ϕ
Table: Syntax of the CL language for contracts.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
44. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
45. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
p
pay
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
46. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
p+
pay or
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
47. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
p + d
pay or delay
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
48. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
O (p + d)
obliged pay or delay
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
49. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
O (p + d)
obliged to pay or delay
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
50. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
OC (p + d)
obliged to pay or delay,
otherwise
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
51. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
OO( )(p + d)
obliged to pay or delay,
otherwise must
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
52. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
OO(p•p)(p + d)
obliged to pay or delay,
otherwise must pay twice.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
53. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
[ ]OO(p•p)(p + d)
after obliged to pay or delay,
otherwise must pay twice.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
54. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
[e]OO(p•p)(p + d)
after exceeding the bandwidth limit, obliged to pay or delay,
otherwise must pay twice.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
55. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
[e]OO(p•p)(p + d)
Always after exceeding the bandwidth limit, obliged to pay or delay,
otherwise must pay twice.
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
56. Bob: “Did you actualy produce anything?”
“Or you are philosopher also?”
The logic, that we called CL, for contracts logic, is a simple language, with
concise logical syntax:
[e]OO(p•p)(p + d)
Always after exceeding the bandwidth limit, obliged to pay or delay,
otherwise must pay twice.
C := φ | OC(α) | P(α) | FC(α) | C → C | [δ]C | ⊥
α := a | 0 | 1 | α×α | α · α | α + α
δ := a | 0 | 1 | δ×δ | δ · δ | δ + δ | δ∗ | ϕ?
ϕ := φ | 0 | 1 | ϕ ∨ ϕ | ϕ ∧ ϕ | ¬ϕ
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 17 / 69
57. No Syntax without Semantics
The syntactic concepts of the CL language are
given meaning through semantics.
Logic is a language with clear mathematical in-
terpretation given by the semantic rules in the
form of a mathematical object.
I picture the semantic object of CL incremen-
tally:
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
58. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world” W1
Q
R
∧P Q
PW1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
59. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
R
QP
W1
∧P Q
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
60. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
3 Dynamic L.: “Label arrows with simple
action names”
d
n
p
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
61. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
3 Dynamic L.: “Label arrows with simple
action names”
4 Synchrony: “Complicate labels to Sets of
simple actions”
{p}
{n}
{d,p}
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
62. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
3 Dynamic L.: “Label arrows with simple
action names”
4 Synchrony: “Complicate labels to Sets of
simple actions”
5 Determinism: “No two arrows with same
label”
{p}
{p}
{d,p}
{n}
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
63. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
3 Dynamic L.: “Label arrows with simple
action names”
4 Synchrony: “Complicate labels to Sets of
simple actions”
5 Determinism: “No two arrows with same
label”
{p}
{n}
{d,p}
{n}
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
64. No Syntax without Semantics
I picture the semantic object of CL incremen-
tally:
1 Propositional L.: “A set of true
propositions defining the world”
2 Deontic L.: “Set of different propositional
worlds connected through arrows”
3 Dynamic L.: “Label arrows with simple
action names”
4 Synchrony: “Complicate labels to Sets of
simple actions”
5 Determinism: “No two arrows with same
label”
6 Deontic Markers: “Mark worlds as good or
bad w.r.t. some simple action”
{p}
{n}
d
d
p
p
n {d,p}
{n}
W
W2
3
W1
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 18 / 69
65. Theoretical contributions
for experts only
Formalization of contracts (modelling / reasoning / tools):
1 A Contract Logic CL with
1 dynamic modality over synchronous actions,
2 deontic modalities over ∗
-free synchronous actions,
3 reparations attached to deontic modalities directly,
4 actions with complex structure (synchronous also)
5 all these concepts as first class citizens
2 semantics of CL on kripke-like normative structures
3 actions done at the same time (using synchrony concept)
4 deterministic actions
5 CTDs and CTPs as syntactic language constructs
6 can express temporal notions like “always” and “eventually”
7 model checking of contracts
8 run-time monitoring of contracts
1 using alternating automata
2 based on a compositional trace semantics
3 with a full fledged example of English contract
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 19 / 69
66. Theoretical contributions
for experts only
For general theoretical and logic community:
1 SKA – Synchronous Kleene Algebra theory
1 SKAT – SKA with Tests (for resoning about programs with synchrony)
2 models as sets of (guarded) synchronous strings
3 Kleene-style representation theorems using special automata
4 completeness results and decidability results for both
5 more results for ∗
-free restricted actions
2 PDL with synchronous actions (decidable)
3 DDL with ∗
-free synchronous actions
(decidable using finite tree model property)
4 A nontrivial combination of logics: PDL + DDL + synchrony (under
special restrictive requirements), called CL
5 CL has the tree model property but not finite
6 CL captures many natural properties of contracts
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 20 / 69
67. Possible applications of CL
Legal documents drafting and analysis
consistency checking
property checking
visualization
semi-automatic negotiation
run-time monitoring
Web services – at the Service Level Agreement (SLA)
Programming
Model complex behavioral interfaces
Express more complex pre-post condition like contracts
Express desired behavior of components in an open environment
Regulate behavior of intelligent agents in multi-agents systems
... whatever you may think of ...
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 21 / 69
68. What to take home?!
A logic, called CL, for modelling/writing contracts (legal, electronic,
programming, agents, concurrent, Internet).
Use CL to check properties on the modelled contract (ask questions).
Use the CL logic to monitor your/other’s actions to be sure that they
respect the contract agreed upon.
The CL logic has:
obligations, permissions, and prohibitions
reparations attached to these
dynamic modality to talk about “what happens after”
actions with complex structure
concurrent/synchronous actions (“actions done at the same time”)
a mathematical basis for the actions as Synchronous Kleene Algebra
Many interesting open research questions for you to work on...
C. Prisacariu @ OSLO Contracts Logic – CL PhD Defence 22 / 69
