Human-Computer Interaction 3e Dix, Finlay, Abowd, Beale
Sections 17.2.1 and 17.2.2 give two reasons for using formal methods in HCI: communication and analysis. These are focused on the sort of mathematical models found in chapter 17. However, there are other sort of 'formal' modelling in HCI: dialog notations are formal models of the syntax of the humancomputer conversation, hierarchical task analysis is a formalisation of the task structure, some cognitive models are effectively formal models of the user's mind.
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Very similar arguments apply to dialog notations as to more mathematical notations. HTAs are certainly used for communication, but perhaps not so much for analysis. Cognitive models are aimed more towards analysis (e.g. learning complexity with TAG, timing with KLM).
Some additional cons:
Some additional pros:
Some issues in choosing an appropriate formalism
Other exercises in this chapter
ex.17.1 (ans), ex.17.2 (ans), ex.17.3 (ans), ex.17.4 (ans), ex.17.5 (tut), ex.17.6 (tut), ex.17.7 (tut), ex.17.8 (tut), ex.17.9 (tut), ex.17.10 (tut)
all exercises for this chapter