Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 1
Four valued logic
for Analysts
Dr. Jim Arlow and 

I...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 2
Secrets of Analysis
• This course is based on Chapte...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 3
• We will look at information types in Generative An...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 4
• In GA you iterate through the following four steps...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 5
GA information metamodel summary
The section tag ref...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 6
• Models key information types for GA

• A conceptua...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 7
The 7 GA information types
Type Semantics
Informatio...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 8
• The 7 GA information types comprise a pragmatic se...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 9
• Each piece of information has:

• Type - one of th...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 10
• Information results from a communication of some ...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 11
• Each piece of Information has an associated toDoL...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 12
• A Resource is Information that
refers to an ident...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 13
• When you track Resources, it is important to know...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 14
• A Question is just that – a query
about some aspe...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 15
• Questions are the central mechanism of M++ (see
“...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 16
• Recover meaning by obtaining more precise Informa...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 17
• A Proposition is a statement about the system
or ...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 18
• GA is evidence driven - nothing is accepted or re...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 19
• Two-valued, Aristotelian logic, in which proposit...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 20
• The truth status of a Proposition is always deter...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 21
• A Proposition that is Maybe needs more analysis

...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 22
• To cut through the human tendency to delete, dist...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 23
• A Proposition in the Maybe state may actually be ...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 24
• Declarative - use simple, declarative statements
...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 25
• There are 2 main states - Analyzing and Analyzed
...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 26
• From observation:

• Typically pretty reliable be...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 27
Beware your tendency to…
Ignorance: when you change...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 28
• M++ consists of 17 distinct
patterns of communica...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 29
• An Information type specifically for encouraging
...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 30
• A specification of what should be implemented:

•...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 31
• A detailed discussion of requirements is out of s...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 32
• The key activity of OOA is
discovering or, more
o...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 33
• The link between the UML model and the
ProjectGlo...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 34
• Defining Terms is a major activity in GA

• It ca...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 35
• The definition of a Term must be:

• Clear – use ...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 36
• Universal - the dictionary entry - an accepted an...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 37
• You should share as much information as you can w...
FourvaluedlogicforAnalysts
© 2017 Clear View Training Limited, v1.0 38
• In this presentation we have explored the informa...
Nächste SlideShare
Wird geladen in …5
×

Four Valued Logic for Business and OO Analysts

237 Aufrufe

Veröffentlicht am

In this presentation, we present the "Secrets of Analysis" approach to logic. Simple, two-valued logic is inappropriate for most Business and OO Analysis activities. We present a richer, four-valued logic that allows the analyst to deal with common problems in Business and OO analysis in a more powerful and structured way.

Veröffentlicht in: Daten & Analysen
  • Als Erste(r) kommentieren

Four Valued Logic for Business and OO Analysts

  1. 1. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 1 Four valued logic for Analysts Dr. Jim Arlow and Ila Neustadt www.clearviewtraining.com
  2. 2. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 2 Secrets of Analysis • This course is based on Chapter 10 from our book, “Secrets of Analysis” • A full table of contents for the book can be found on the website below • You can buy the book at the website or on the Apple iBooks Store www.clearviewtraining.com/secrets-of-analysis.html
  3. 3. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 3 • We will look at information types in Generative Analysis (GA) and how to process them effectively using non- Aristotelian four-valued logic Introduction
  4. 4. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 4 • In GA you iterate through the following four steps until you have enough information to move on to more formal analysis using UML models: 1. Collect information (see “Secrets of Analysis”) 2. Classify the information using GA information types (next slide) to create GA information artifacts 3. Analyze the information artifacts 4. Generate new, more valuable, artifacts by transformation of existing artifacts (using M++) Processing information in GA Any kind of information can be an input to GA!
  5. 5. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 5 GA information metamodel summary The section tag refers to a section in “Secrets of Analysis”
  6. 6. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 6 • Models key information types for GA • A conceptual model where «concept» represents a concept rather than a class • «concept» has a single tag, section, that refers to a section in our book “Secrets of Analysis” • Each «concept» has attributes that represent specific features of the information types that are important in GA • Attributes have been hidden on the summary view on the previous slide • We will look at each concept in detail over the next few slides… About the metamodel…
  7. 7. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 7 The 7 GA information types Type Semantics Information A communication of some sort subject to the three filters of deletion, distortion and generalization. May have an associated toDoList of Actions Question Questions arise from considering Information and applying M++ Proposition A Proposition is a statement about the system/problem domain with value: Maybe – there is insufficient evidence to decide True – there is evidence to support the truth of the Proposition False – there is evidence to support the falsehood of the Proposition Undefined – the Proposition is ill-formed and undecidable. The evidence (if any) is contradictory Resource Resources are things that you identify that may help you in your project Idea Ideas are just that - things that come to you when you are performing analysis that might be useful later Requirement A statement of what the system should do (functional requirement) or how the system should do it (non-functional requirement) Term Terms are words or phrases defined in the ProjectGlossary
  8. 8. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 8 • The 7 GA information types comprise a pragmatic set of information types that we find works well in most circumstances • You can add your own, project specific, information types: • Always work with as few information types as possible • Define distinct types that have differences that make a difference • Only use types that add real benefit to your project - ask “what does this information type give me?” • Never waste time arguing about the type of a particular piece of information - classify it quickly, and then refine the classification as you find out more Other information types
  9. 9. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 9 • Each piece of information has: • Type - one of the 7 information types • Attributes - useful data about the information • Actions - things you can do with the information • Actions are the key to GA - information needs to be used Analysing the information GA information types are never an end in themselves!
  10. 10. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 10 • Information results from a communication of some kind: • Text and speech (including video and recordings) • Non-verbal communication e.g. examining artifacts or processes Information Information attribute Semantics content Describes the piece of Information in text and (optionally) graphics isCompleted Indicates how important the Information is to the project notes A catch-all where you can list arbitrary metadata about the Information that doesn't fit anywhere else toDoList A list of Actions that describe what needs to happen to the Information creator The Resource that created the piece of Information source The Resource that sourced the Information. Gives traceability from features in your models back to the specific Resources. When you are presenting your results to stakeholders, they often ask “how do you know that?” or “who told you that?” helpers A Resource that knows something specific and useful about the Information, and that can help you to analyze it. Only list helpers that are not obvious and that have something important to say
  11. 11. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 11 • Each piece of Information has an associated toDoList of Actions • An Action is where you describe what needs to happen to the Information • Actions drive the GA process forwards • We kept our model of Actions basic because details are often project specific: • Actions impact project management, planning etc. Action Action attribute Semantics description Describes the Action in text and (optionally) graphics isCompleted Set to True when the Action has been completed, otherwise is False … You can add your own attributes depending on the specific needs of your project e.g. scheduling, priorities, etc.
  12. 12. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 12 • A Resource is Information that refers to an identifiable, locatable thing, person or role that provides a source of Information for your project • The “who's who” and “what's what” of a project • It is vitally important to keep track of key Resources: • This is very often left to the uncertain mechanisms of chance and networking. This is OK for small projects, but doesn’t scale well Resource
  13. 13. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 13 • When you track Resources, it is important to know how to locate and use them! Resource attributes Resource attribute Semantics locations How you can access the Resource e.g. an address for a person or role, a map location for a thing, or a URL for a document. Each location must make the Resource easy to access, so include all necessary information, including maps if appropriate uses The specific ways in which the Resource may be useful to your project. Only specify uses that are specific and not obvious - there's no point listing obvious or general uses such as “source of information”! role The job title of a human Resource or the role of the Resource with respect to the system
  14. 14. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 14 • A Question is just that – a query about some aspect of the system that needs an answer • The answer is a set of Propositions (see later) that together constitute an answer to the Question • You answer Questions by research: 1. Identify Resources that can serve as sources of answers 2. Find answers by interviewing or studying Resources Question
  15. 15. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 15 • Questions are the central mechanism of M++ (see “Secrets of Analysis”) and of all types of analysis • The essence of GA is being able to generate good Questions • Generate Questions by examining Information and asking yourself what it actually means: • Use M++ to identify deletions, distortions, generalizations and presuppositions to uncover the meaning of the communication Questions in GA
  16. 16. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 16 • Recover meaning by obtaining more precise Information: • All communications have some meaning, even if that meaning is only "I am communicating" • Programming - extend someone’s map of reality with new meanings: • Use Questions to take someone to the edge of their map and gently push them beyond • Deprogramming - change maps that are not useful by questioning them: • Use Questions to demonstrate that a map is un-sane (see “Secrets of Analysis) • Use M++ and the Milton Model to reconfigure their map (see “Secrets of Analysis) Three uses of Questions
  17. 17. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 17 • A Proposition is a statement about the system or problem domain whose status may be True, False, Maybe or Undefined - four valued logic • The most complex of the GA information types - their behaviour is the basis of GA Proposition
  18. 18. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 18 • GA is evidence driven - nothing is accepted or rejected without specific evidence • The X-Files™ principles: • “Trust no one” • “The Truth is out there” • Or, if you prefer, the Royal Society principle: • Nullius in verba - take nobody’s word for it! Proposition attributes Proposition attribute Semantics status May take one of the values Maybe, True, False, or Undefined. The status is assigned on the basis of evidence accumulated to support it evidence The specific facts on which the status of a Proposition is based
  19. 19. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 19 • Two-valued, Aristotelian logic, in which propositions are either true or false is generally insufficient to deal with the real-world in all but the simplest of cases: • Much of the suffering in the world arises from the inappropriate application of Aristotelian logic - can you find your own examples? • GA is based on a richer, more flexible four valued logic, after von Neumann and Korzybski (General Semantics) Four-valued logic
  20. 20. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 20 • The truth status of a Proposition is always determined by analysis of the evidence Maybe, True, False, Undefined Truth status Semantics Maybe The evidence collected to date is either insufficient to determine the truth status of the Proposition or it hasn't been analyzed yet. This is the default value True The Proposition has been verified as a fact because there is evidence to support the truth of the Proposition False The Proposition has been verified as a falsehood because there is evidence to support the falsehood of the Proposition Undefined All the evidence that can be collected has been collected and analyzed. On the basis of this, the Proposition has been found to be undecidable. The evidence may be contradictory, or it may simply be impossible in practice to collect sufficient evidence. Also, the Proposition may just be a swindle. For a discussion of Nietzschean swindles, see “Secrets of Analysis”
  21. 21. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 21 • A Proposition that is Maybe needs more analysis • A Proposition that is True expresses a truth about the domain: • These are important Propositions, and you generally need to record them somehow • True Propositions may generate a Requirement for the system • A Proposition that is False expresses a falsehood about the domain: • You may be able to discard it, but in many domains there are persistent falsehoods that come up again and again. In this case keep it! • A Proposition that is Undefined is just noise and contributes nothing: • You can generally delete noise unless it is persistent noise in which case you keep it The meaning of Propositions
  22. 22. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 22 • To cut through the human tendency to delete, distort and generalize to support presuppositions, Proposition status must be based on the evidence • You must be able to track this evidence back to the real world (see “Secrets of Analysis”) • The evidence attribute summarizes the data supporting the Proposition's assigned status: • This might be as simple as, "See the Vision Document paragraph 2”, or, "Private communication with Dr. Armitage" • In complex cases, it could be a fairly detailed description of the rationale behind the assigned status The status is based on the evidence
  23. 23. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 23 • A Proposition in the Maybe state may actually be a propositional function whose value depends on the value of one or more multi-ordinal terms (a term that may take many possible values) • You must define the the multi-ordinal terms sufficiently to move the state to True, False or Undefined Beware of propositional functions Proposition Truth value P1: “The library holds periodicals” Maybe until verified by evidence P2: x < 25 Maybe - a propositional function whose truth depends on x P3: 23 < 25 True P4: 25 < 23 False P5: cat < 25 Undefined - meaningless Note: An analysis of propositional functions leads directly to 4-valued logic!
  24. 24. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 24 • Declarative - use simple, declarative statements • Simple - the simpler the Proposition, the more likely that you can analyze it correctly: • Short sentences with no logical operators (if, else, and, or, not) • Structured - Propositions usually have one of two structures: • SVO - subject, verb, object - these are about actions e.g. “The Librarian adds books to the library catalog.” • SLVC - subject, linking verb, complement - these are about description e.g. “Books have an ISBN.” • Positive - must always be expressed in the positive: • Look for “not” and remove it • Atomic - decompose complex Propositions: • Look for “if”, “else”, “and”, “or” and split Writing good Propositions
  25. 25. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 25 • There are 2 main states - Analyzing and Analyzed • True Propositions can generate Requirements • False and Undefined Propositions may be kept to defend arguments Proposition lifecycle
  26. 26. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 26 • From observation: • Typically pretty reliable because they are objective • e.g. “The library card catalog contains cards” - go and take a look! • From inference: • Typically less reliable because not necessarily objective • Inference is a process of logical reasoning about the real world that almost invariably involves the processes of deletion, distortion and generalization: • e.g. “Borrowers may only borrow a book for 28 days” • P1: There are things called borrowers 👍 😸 • P2: There are things called books 👍 😸 • P3: A borrower may borrow a book for exactly 28 days (no more and no less) 👎 💩 • P4: A borrower may only borrow one (a) book 👎 💩 • Use M++ to analyze inferences (see “Secrets of Analysis”) Finding Propositions
  27. 27. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 27 Beware your tendency to… Ignorance: when you change the information to fit the map. Learning: when you change the map to fit the information.
  28. 28. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 28 • M++ consists of 17 distinct patterns of communication • For each pattern, there is a set of questions to help you clarify deletions, distortions and generalizations in order to uncover the missing information • See “Secrets of Analysis” for a discussion of M++ and many examples of how to use it Analysing a Proposition with M++ www.clearviewtraining.com/secrets-of-analysis.html
  29. 29. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 29 • An Information type specifically for encouraging creativity - a catch-all where you can capture any ideas about the system • Ideas are important and need to be captured • Many projects have no formal way to do this! • Working with Ideas: 1. Generate the Idea - use a brainstorm, mind-mapping, dialogue mapping or some other creative technique (see “Secrets of Analysis”) 2. Record it 3. Incubate... (at least half an hour) 🐔 4. Analyze the Idea to generate Resources, Propositions, Requirements, Terms, Questions and more Ideas Idea
  30. 30. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 30 • A specification of what should be implemented: • Functional - what behavior the system should offer • Non-functional - a specific property of the system, a constraint on the system • The exact specification of a Requirement will depend on your particular project • Requirements have a status of Candidate or Confirmed • Candidate - just speculation – it must be Confirmed by getting it reviewed by stakeholders and other project members • Confirmed - a definite Requirement that will be handled according to its priority. Usually has been signed off by stakeholders and project managers (include reference in notes) Requirement
  31. 31. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 31 • A detailed discussion of requirements is out of scope for this presentation. See “Secrets of Analysis” for more details More about requirements…
  32. 32. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 32 • The key activity of OOA is discovering or, more occasionally, creating an ontology for the problem domain • In GA, you express this ontology as a Literate UML model supported by a ProjectGlossary that comprises a set of one or more Terms Term
  33. 33. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 33 • The link between the UML model and the ProjectGlossary is the keystone of Literate Modelling, and without such a link, Literate Modeling isn't really possible • For more information about Literate Modelling: • See our SlideShare on Literate Modelling • Yes - you guessed it! Read “Secrets of Analysis” Literate Modelling
  34. 34. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 34 • Defining Terms is a major activity in GA • It can help resolve many problems within the business Term attributes Term attribute Semantics content The term as text e.g. Librarian definition A dictionary definition for the Term partsOfModel Pathnames to parts of the UML model that correspond to the Term partOfSpeech Typically, Noun or Verb (keep it simple!) status Candidate – the Term hasn't been analyzed yet (the default) Primary – it is a key Term that should always be used within the project Secondary – it is a synonym of a key Term that may be used externally to communicate with stakeholders, but which must never be used within the project synonyms Each Term may be associated with zero or more other Terms that are its synonyms. Each synonym must be a Secondary Term because there can only be one Primary Term with a given meaning within the project
  35. 35. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 35 • The definition of a Term must be: • Clear – use the principles of Structured Writing that we discuss in Chapter 3 of, “Secrets of Analysis” • Unambiguous – apply M++ to check your definitions (see “Secrets of Analysis”) • Concise – distill the meaning of the Term into the shortest possible definition. Long definitions tend to go unread and unused and are more subject to ambiguity • General – choose the most general definition that works Defining Terms
  36. 36. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 36 • Universal - the dictionary entry - an accepted and reasonable meaning • Domain - a common usage across a particular business domain • Company - universal across a particular company • Group - restricted to a particular group within a company - resolve this to a more generally accepted term if you can: • DANGER - drift of meaning! • Individual - a usage restricted to a particular individual within a company - you must resolve this to a more generally accepted Term • For the ProjectGlossary choose the most general meaning that makes sense for your project - this is often Universal, Domain or Company Generality of Terms Green - best PrimaryTerms Amber - may be OK Red - just say no
  37. 37. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 37 • You should share as much information as you can with everyone on the project, but there may be security restrictions • Ideally, you should capture the information types in your UML modelling tool, but check that: • The tool can handle arbitrary information types well • The information remains accessible e.g. does the tool have good search facilities, does everyone have access to it? • You can also use a Content Management System to store information: • Advanced Content Management Systems such as Plone allow the definition of information types Managing the information
  38. 38. FourvaluedlogicforAnalysts © 2017 Clear View Training Limited, v1.0 38 • In this presentation we have explored the information types most used in Generative Analysis • We have seen how to process these information types • We have explained the necessity of four valued non- Aristotelean logic in GA and in analysis in general • We hope you have enjoyed this presentation and will support us by purchasing a copy of “Secrets of Analysis”! Summary www.clearviewtraining.com/secrets-of-analysis.html

×