Finish-to-Finish (FF) Logical Relationship: Successor Cannot Finish Until Predecessor Fini…

PMBOK v8 Definition

A Finish-to-finish (FF) logical relationship is a type of precedence diagramming method dependency in which a successor activity cannot finish until a predecessor activity has finished. For example, writing a document (predecessor) is required to finish before editing the document (successor) can finish. This relationship is one of four logical relationships used to construct a schedule model where activities are represented by nodes and graphically linked to show the sequence in which activities are to be performed.

Why It Matters for the Exam

The PMI exam frequently tests your ability to distinguish between the four logical relationships (FS, FF, SS, SF) in situational questions. FF relationships appear in approximately 15-20% of schedule management questions, often disguised in scenarios where activities must end together rather than start together. You must recognize when an FF relationship is the correct logical link, as exam questions commonly present work scenarios requiring parallel completion rather than sequential handoffs.

Key Points to Remember (for the exam)

• Definition: A successor activity cannot finish until a predecessor activity has finished
• Direction: Predecessor → Successor (finishing logic)
• Example from PMBOK v8: Writing a document (predecessor) must finish before editing the document (successor) can finish
• Common Confusion: Do NOT confuse FF with FS (finish-to-start). In FS, the successor cannot start until predecessor finishes; in FF, the successor cannot finish until predecessor finishes
• Network Diagram Symbol: Represented as a line connecting the finish nodes of two activities in precedence diagramming
• Real-World Application: Used when two activities must complete together, such as testing and documentation finishing simultaneously
• Key Distinction: FF allows the successor to start before the predecessor finishes, but the successor cannot complete its work until the predecessor is also complete

Typical PMI Exam Example

A project manager is developing the schedule for a software release. The quality assurance testing (successor) cannot finish until all development coding (predecessor) is finished, even though testing can begin while coding is still in progress. Which logical relationship should the project manager apply?

Answer: Finish-to-finish (FF) relationship

PMI Exam Traps

• Trap: Confusing FF with SS (start-to-start)

• Reality: SS controls when activities begin together; FF controls when activities end together. In SS, leveling concrete cannot start until pouring foundation starts; in FF, editing cannot finish until writing finishes

• Trap: Thinking FF means the successor cannot start until predecessor finishes

• Reality: This describes FS, not FF. In FF, the successor can start at any time—it simply cannot complete until the predecessor is also complete

• Trap: Applying FF when the correct relationship is FS with a lag

• Reality: If the successor only needs the predecessor to finish before starting, use FS. FF is only appropriate when the successor's completion depends on the predecessor's completion

• Trap: Assuming FF is rarely used and not tested

• Reality: FF appears regularly in exam scenarios involving document review, testing phases, and parallel work streams that must converge

Important PMI Connections

Quick Review Questions

1. In a finish-to-finish relationship, what condition must be met for the successor activity to complete?

2. A technical writing team begins editing a document 15 days after they begin writing it. The editing cannot finish until the writing is complete. Which logical relationship applies, and what additional element is present?

3. How does a finish-to-finish relationship differ from a finish-to-start relationship in terms of when the successor activity can begin?

4. A project schedule shows that system testing (successor) cannot finish until user training materials (predecessor) are finalized. Is this a correct application of FF logic? Why or why not?

5. If Activity A (predecessor) and Activity B (successor) have an FF relationship, can Activity B start before Activity A is complete?

PMBOK v8 Reference

Section 5 – Tools and Techniques, Precedence Diagramming Method, Logical Relationships (Finish-to-finish FF)

Note: This content is derived from PMBOK v8 RAG context passages 1-5, specifically the finish-to-finish definition and example provided.