Mistakes and Difficulties in Working with TOC Logical Tools


Jelena Fedurko

It is a helpful guide to improve quality of work with the TOC logical tools.

It is Jelena’s third book about  TOC logical tools that follows Behind the Cloud (2011), and Through Clouds to Solutions (2013).

Mistakes and Difficulties in Working with TOC Logical Tools focuses on typical errors in wording, content, logic and purpose of Clouds and Current Reality Trees  and looks into confusion between necessity and sufficiency logic.

This book is a textbook. It looks into a type of mistake one by one, explains why it is a mistake, shows examples, and offers rules and guidelines how to avoid the mistakes.

The book reflects Jelena’s intensive involvement with TOC since 1999, her background in linguistics and management, and over 30 years of teaching and consulting.

Table of Contents

  • About the Author
  • From the Author

Part 1. Typical mistakes in Clouds 

  • Chapter 1. Mistakes in wording the entities in the Cloud
  • Chapter 2. Mistakes in the logic of the Cloud
  • Chapter 3. Checking Cloud wording and logic – A case for analysis
  • Chapter 4. Checking Cloud wording and logic – Answers to the case
  • Chapter 5. Mistake: The statement in A is a simple summation of the statements in B and C
  • Chapter 6. Mistake: The statement at the tip of the arrow speaks about the same as the statement at the tail of the arrow, only in a more generic way or with different wording
  • Chapter 7. Mistake: D does NOT endanger C, and/or D’ does NOT endanger В
  • Chapter 8. Mistake: You have put your solution in D or D’ in the Cloud that you plan to use for getting a buy-in
  • Chapter 9. Mistake: D and D’ in an UDE Cloud are worded as an internal dilemma regarding a decision for the future
  • Chapter 10. Mistake: Mirror reflection between an UDE, B and D in the UDE Cloud
  • Chapter 11. How to avoid mistakes in UDEs – 10 UDE Rules
  • Chapter 12. A brief recap on 7 typical mistakes in surfacing assumptions in Clouds and 4+2 Assumption Rules
  • Chapter 13. Some thoughts about a claim that an objective of a project should be an Injection to a Cloud
  • Chapter 14. Frequent sloppy work when Cloud owners want to use the Cloud for justification of their solution
  • Chapter 15. The Cloud is NOT for goal-setting
  • Chapter 16. A confusing claim that the Cloud is BASED ON Necessity logic

Part 2. Mistakes and difficulties in building the Current Reality Tree (CRT) 

  • Chapter 17. Two approaches to CRT
  • Chapter 18. Mistake: At the bottom of the CRT you state that the Core Problem of the system is the absence of your solution
  • Chapter 19. Mistake: At the bottom of the CRT you put a cause that is outside of your control

Part 3. Frequent confusion regarding Necessity Logic versus Sufficiency Logic as related to TOC logical tools

  • Chapter 20. A brief recap on the distinction between Necessity and Sufficiency
  • Chapter 21. Sufficiency inside the cause
  • Chapter 22. When an announced cause and effect relationship depends on an implied meaning
  • Chapter 23. A confusing claim that CRT and FRT are BASED ON Sufficiency logic
  • Afterword

Mistakes and Difficulties in Working with TOC Logical Tools is 170 pages, soft covers.

To get information about the book and to purchase a hard copy – please contact jelena@tocexpert.com orjelenafedurko.gs@gmail.com

The book can be also purchased as an eBook at


Jelena is a TOC Expert in tocExpert, International Director of TOC Strategic Solutions, and a co-founder and co-president ofTOCPA – the Theory of Constraints Practitioners Alliance.  She has worked with companies in the areas of production, project management, supply chain, distribution, and retail in more than 15 countries helping with TOC implementations.

Other books by Jelena Fedurko:

Behind the Cloud – Enhancing logical thinking (2011)

Through Clouds to Solutions – Working with UDEs and UDE Clouds (2013)

Mistakes and Difficulties in Working with TOC Logical Tools (2014)

A Good Strategy and Tactic Tree – Rules, Examples, Typical mistakes, Exercises with Answers (2016)


This combination of material will enable you to build good enough clouds and equip you with good understanding and practical tips how to work with assumptions and develop injections.

If you want to have further understanding of different types of Clouds and build solid knowledge on how to develop UDEs and how to work with UDE Clouds:

To get solid understanding of how to work with the Strategy and Tactic Tree:

What readers say about Jelena’s books:

Every so often a book comes along that fills a gap, that makes us say, “That’s just what I was looking for.” Many of us in the TOC community consider the cloud to be our most powerful and most frequently used TP tool. We users will appreciate the careful attention Jelena Fedurko has given to our favorite construct, the cloud. Her knowledge of this tool, and her understanding of the logic behind it, are clearly expressed in these pages. The ample examples and detailed explanations make this unquestionably the most powerful book on clouds yet written. She has upgraded all of our knowledge, and provided a permanent addition to the TOC body of knowledge. We are all in her debt. If you are serious about TOC, you must own this book. – Forward to Behind the Cloud by Dr. Alan Leader

Your book [Behind the Cloud] has been a perfect support for me to dig further into the Cloud’s mechanisms, and its relationship with the other TP tools.

I’m quite a TOC newcomer, but already a big fan. I’m getting into Clouds and I heard very good feebdacks about your book.

I have read your book Behind The Cloud and enjoyed it very much. I learned many new ideas.  Thank you.

We recently acquired the book “Behind the Cloud” by Jelena Fedurko. An excellent guide to raising assumptions in a cloud!

I am one of the guys that I watched your presentation back in Germany about the UDE clouds and I also bought your new book [Through Clouds to Solutions]. I just wanted you to know that I found your book to be just great !!! you did an excellent job setting it up for all the rest of us. I found it extremely useful – I have read it 10 times and I advise it all the time. It is really excellent !!

I just wanted to thank you for your well written book [Mistakes and Difficulties in Working with TOC Logical Tools]. This is a great read for anyone wanting to REALLY understand clouds and CRTs.

Your previous books have been so good, I look forward to receiving your S&T Book.

All of your books are excellent.  Clean, clear, quick, no-nonsense teaching material.

I have begun using “Through Clouds To Solutions” to properly frame UDEs (reference 10 Rules) – & intend using it extensively to make the UDE clouds and then onwards to the core conflict & CRT, using the Three Cloud Method. This is to acknowledge that your work has been a ‘big big help’ – difficult to imagine how I would have managed it without your explanations,  error examples & workbook exercises… I feel sorry for the many TOC practitioners who are wanting to master the use of  cloud technique but are either unaware or not fully connected to your work, for whatever reasons – pity that they are not benefiting from your immense contribution in this area…..!!

Your book [Mistakes and Difficulties in Working with TOC Logical Tools] arrived last night it is fantastic!!! I have not stopped reading it.