Issues for Mailing list of the Semantics of Business Vocabulary & Business Rules Finalization Task Force

List of Open Issues. Other options: All Issues; Closed Issues.

(red=unresolved; yellow=pending Board vote)

Problem Description:


Clause 8.7 defines 'integer' as "a number with no fractional part".  But the concept 'number' to which this definition appeals is not defined, and the entry does not cite a source for the definition.  'number' should be defined as well.


SBVR clause 8.7 defines the fact-type 'integer is-less-than integer'.
This is a narrow definition of the 'less-than' concept, which applies, with the same semantics, to 'numbers' and to arbitrary quantities.  'Quantity' is the general concept on which comparison for less and greater is defined for business purposes.  It is the concept for which is-less-than should be defined in 8.7.


In Annex D, 'is less than' is used as a fact-type for prices and durations in several places, but it is never defined.  This usage requires a wider definition of the is-less-than fact-type that is defined in 8.7, namely a definition on 'quantity'.  D.2.3.3 defines 'duration' as "a quantity of time", but the term 'quantity' is not a vocabulary entry in either 8.7 or Annex D. And D.2.3.3 defines the fact-type 'duration is-at-most duration', but it has the same semantics as quantity is-less-than (or equal to) quantity.  It is clear that this example is a model for the definition of "measurement" vocabularies, and 8.7 should provide the base term 'quantity' to support that.



* Proposed solution:


(1) define the term 'quantity' in SBVR, e.g.,
  Definition: a determinate or estimated amount [of a thing]
  Definition: the aspect in which a thing is measurable in terms of greater, less or equal
  Source: MW
  Note: The concept quantity can be elaborated into mathematical systems, such as integer and real numbers, and into systems of measures.  This specification elaborates only the concepts for integer, because they are commonly used in structural rules (See x.x).  For measurement systems and units of measure there are accepted vocabularies and perhaps standard ontologies, but the specification of such a vocabulary is beyond the scope of this specification.


(2) replace the the fact-type 'integer is-less-than integer' with the fact-type 'quantity is-less-than quantity'.


(3) add the concept 'number'
  Definition: a [quantity] belonging to an abstract mathematical system and subject to laws of succession, addition and multiplication
  Source: MW


(4) make integer a subtype of number, and number a subtype of quantity.


(5) correct the "term" style for 'number' in the definition of integer in 8.7, and for 'quantity' in the definition of duration in D.2.3.3.


(6) In D.2.3.3, add to the definition of duration is at most duration:
  Synonymous form: duration is less than or equal to duration

Introduce "quantity" as a defined concept.
Introduce "number" as a category of "quantity".
Define "integer" as a category of "number".

Referencing dtc/06-03-02, section 8.1.2 defines four basic modalities (necessity, possibility, obligation, permissibility).  This agrees with table 10.2. 

Section 10.1.2 defines a total of eight modes of thinking, of which one (contingency) "is not relevant in a business rules context."   This leaves three alethic modes (necessity, possibility, and impossibility), and four deontic modes (permission, obligation, nonpermission/forbidden/prohibition, and non-obligation). 

Table I.3 lists six  modal operators: necessary, possible, impossible, obligatory, permitted, forbidden.  This matches section 10.1.2 if we assume that non-obligation (like contingency) is not relevant. 

Section 12.2.1 defines six forms of business rule statements: obligation, prohibitive, restricted permissive, necessity, impossibility, restricted possibility.  The two restricted forms are defined as composites of either permission or possibility and a condition.  Notice that unrestricted permissive and unrestricted possibility statement forms are not mentioned. 

Section F.1.1 describes eight statement forms: obligative statement, prohibitive statement, restricted permission, unrestricted permission, necessity, impossibilty, restricted possibility, unrestricted possibility.  It has both of the forms (unrestricted permission, unrestricted possibility) that seem to be missing from section 12.2.1. 

Section 10.1.2 defines prohibition but not impossibility. 

Suggestions: 

1. It seems that section 12.2.1 should include the two unrestricted forms: unrestricted permission, unrestricted possibility.  Alternatively, section F.1.1 should be aligned with section 12.2.1 -- but that seems undesirable since the unrestricted forms do appear in the real world. 
2. Section 10.1.2, in the discussion of deontic modality, should make it clear that "non-obligation" is not relevant, as it already does for "contingency" in the definition of alethic modality. 
3. Make the definition of the restricted forms explicit by defining them in terms of the equivalent logical formulations using the underlying basic modalities plus implications. 
4. Adopt a consistent approach to the negative forms (prohibition, impossibility): 
        a) Adopt one designation for nonpermission/forbidden/prohibition. 
        b) Define impossibility in section 10.1.2. 
        c) Make the definition of the negative forms (impossibility, prohibition) explicit by defining them in terms of the equivalent logical formulations using "not" and the underlying basic modalities. 

Make the following set of changes, based on FTF discussion, with final agreement in the telcon of 01/03/2007.

Location: SBVR Annex H


Issue: Is it legitimate in UML to have bidirectional association names with black triangles indicating direction, as in Figure H.4?


Resolution: none proposed as yet - need to have the question answered first.

Annex H describes a UML profile for Business Object Models in which sentential forms of fact types are shown using a notation similar to that of UML Associations.  UML's profile capability allows for UML to be extended by reusing basic UML notations for new meanings and by adding new notations.  The profile described in Annex H takes advantage of this extensibility.  The verb phrases that appear in diagrams for a fact type are not names of an association.  The arrows do not show an order of association ends, but rather show the direction of reading of the verb phrases with respect to the roles of the fact type.
To make clear that the profile of Annex H is used in figures, the disclaimer under the figures is expanded with a reference to Annex H.
A small change is made to the introduction to Annex H in order to clarify where the profile is being used.

ISSUE NAME: Authorizations & Support for "Dark World" Assumptions PROBLEM: The current approach in SBVR is based on a "light world" assumption (everything permitted unless expressly prohibited). As has been pointed out by Mark Linehan and others, there are cases where the opposite assumption ("dark world") is appropriate (everything is prohibited unless expressly permitted), especially for authoization. PROPOSED RESOLUTION: SBVR already has the support necessary for 'dark world' assumptions; it simply needs to be explained and illustrated. I propose the following text be inserted into SBVR at the appropriate point, perhaps in 12.1. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ (PROPOSED TEXT TO BE INSERTED) Authorizations SBVR makes a ‘light world’(1) assumption about rules. In a ‘light world’, anything that is not expressly prohibited is assumed permitted. Business rule practice indicates that this choice is the appropriate one for the large majority of business problems. Occasionally, practitioners may discover cases in which the opposite assumption is appropriate. In such ‘dark world’ circumstances, anything not expressly permitted is assumed prohibited. Such cases might involve use of, and/or access to, resources that are deemed especially sensitive, dangerous, scarce, and/or valuable. For that reason, it makes sense to grant permission for use and/or access explicitly. Such permissions are often called “authorizations”. SBVR does not offer any specialized support for authorizations. None is needed. Support for authorizations is accomplished as follows: * A rule is expressed to declare that some general area of business activity is prohibited except where expressly permitted (i.e., ‘dark’). * Specific advices of permission, qualified as appropriate, are given to indicate selective authorizations. The following examples illustrate. Example 1. Fact type: person makes payment ‘Dark’ Rule Statement: A person may make a payment only if making the payment is expressly permitted for the person. Advice of Permission Statements: * A senior manager may make a payment. Note: This rule statement could also be expressed: A person may make a payment if the person is a senior manager. * Jane Smith may make a payment. Note: This rule statement could also be expressed: A person may make a payment if the person is “Jane Smith”. Example 2. Fact type: ice road is used by vehicle ‘Dark’ Rule Statement: An ice road may be used by a vehicle only if using the ice road is expressly permitted. Advice of Permission Statements: * An ice road may be used by a vehicle if the ice road is north of the arctic circle. * The ice road with the name, Yukon 12,000 Foot Lake Road, may be used by a vehicle. * An ice road may be used by a vehicle if the average temperature at the southern-most point has been below 0o C for at least 5 days. 1 (footnote) Ronald G. Ross, "The Light World vs. the Dark World ~ Business Rules for Authorization," Business Rules Journal, Vol. 5, No. 8 (August 2004), URL: http://www.BRCommunity.com/a2004/b201.html 

In the final read through of Annex E (EU-Rent example) a few errors of content were noticed.
Corrections are given below. 

Revised Text:
E.2.2.1.1: rental car is assigned to car movement
Necessity:
replace "…car movement is of the car model …" 
with "…car movement is of some car model …"
E2.2.1.2: transfer drop-off branch
Definition:
replace "branch from which the transferred car of a car transfer is picked up"
with "branch at which the transferred car of a car transfer is dropped off"
E.2.2.1.5: pick-up branch
Necessity:
replace "The pick-up branch of a rental may not be changed."
with "The pick-up branch of a rental is not changed."
E.2.2.1.5: rental
Definition:
replace "… specifying use of a car of a car group…"
with "… specifying use of some car of a car group…"
E.2.2.1.9 drop-off branch
replace Necessity "A car may be returned to a location other than …"
with Note "A car may be returned to a branch other than …"
E.2.2.1.10 rental car is of car model
Insert new entry immediately following:
rental car is of car group
Concept Type:		associative fact type
Necessity:		A rental car is of a car group if and only if the rental car is of some car model that is included in the car group. 
E.2.2.1.11 renter is responsible for rental
Necessity
Replace "The renter of a rental may not be changed"
With "The renter of a rental is not changed"
E.2.2.2.5 Page 380, second rule
Rule statement
Replace "If the actual pick-up date/time of each rental is after the end date/time …"
With "If the actual return date/time of a rental is after the end date/time …"
Supporting fact types
Replace "rental has actual pick-up date/time"
With "rental has actual return date/time"
Related facts
Delete "the noun concept 'actual pick-up date/time' is a role that ranges over the noun concept 'date/time'"
E.2.2.2.11.2 First rule
Rule statement
Replace "… is provisionally charged to a credit card …"
With "… is provisionally charged to some credit card …"
 
Repeated error in Necessity for inclusion in a segmentation
In several places the Necessity is incorrectly stated as
 "aaa is included in Bbbbbbb" instead of 
"The concept 'aaa' is included in Bbbbbbb". 
For example, in E.2.2.1.3, city branch:
replace "city branch is included in Branches by Type."
with "The concept 'city branch' is included in Branches by Type."
The same change needs to be made for:
E.2.2.1.6 in-country one-way rental
E.2.2.1.6 in-country rental
E.2.2.1.6 international rental
E.2.2.1.6 international inward rental
E.2.2.1.6 international outward rental
E.2.2.1.6 local one-way rental
E.2.2.1.6 round-trip rental
E.2.2.1.6 walk-in rental
E.2.2.1.7 cash rental
E.2.2.1.7 cash rental price
E.2.2.1.7 driver charge
E.2.2.1.7 extras charge
E.2.2.1.7 penalty charge
E.2.2.1.7 points rental
E.2.2.1.7 points rental price
E.2.2.1.11 corporate renter
E.2.2.1.11 individual customer

 
Characteristics used to define states.
There is a mixture of use of the verb form and the gerund form. The verb form seems better for states. The changes are:
Section	Replace	With
E.2.2.1.6	advance rental being assigned	advance rental is assigned
E.2.2.1.6	advance rental being reserved	advance rental is reserved
E.2.2.1.6	rental being returned	rental is returned
E.2.2.1.9	rental being late	rental is late
E.2.2.1.9	rental being overdue	rental is overdue
E.2.2.1.9	rental car being in need of repair	rental car is in need of repair
E.2.2.1.9	rental car being in need of service	rental car is in need of service
E.2.2.1.9	driver being barred	driver is barred

Disposition:	Resolved

As a result of the vote on Issue 9959, there is a need to clarify and strengthen the Note in front of the Formal Logic Interpretation Table in Clause 10.2, particularly to cover these points:

 

-          a major subset of SBVR has a complete formal logic interpretation whose principles are set forth in Clause 10.1

-          the table will contain:

o        a formal logic interpretation specified in ISO Common Logic based on Clause 10.1

o        a cross-reference to OWL constructs that equivalent to SBVR constructs

-          the current table is incomplete and immature, and will be completed during the SBVR Revision Task Force