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On Ambiguity and Specificity

On Ambiguity and Specificity. Finding the “Sweet Spot”. One of the most difficult challenges in specifying requirements is to make them detailed enough that the can be understood without over constraining the system.

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On Ambiguity and Specificity

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  1. On Ambiguity and Specificity

  2. Finding the “Sweet Spot” • One of the most difficult challenges in specifying requirements is to make them detailed enough that the can be understood without over constraining the system. • The question most often asked is “to what level of specificity must I state the requirements in order to avoid any chance of being misunderstood?”

  3. Ambiguity Example – “Mary Had a Little Lamb” • What does this sentence mean? • Using the keyword or dictionary technique, we focus on the words had and lamb. • “Had” is the past tense of “have”, so we’ll use the definition of “have”.

  4. Ambiguity Example – “Mary Had a Little Lamb” (Cont’d) • have 1a: to hold in possession as . . . 4a: to acquire or get possession of: to obtain (as in “the best to be had”) . . . 4c: ACCEPT; to have in marriage . . . 5a: to be marked or characterized by (to have red hair) . . . 10a: to hold a position of disadvantage or certain defeat . . . 10b: TRICK, FOOL (been had by a partner or friend) . . . 12: BEGET, BEAR (have a baby) . . . 13: to partake of (have dinner) . . . 14: BRIBE, SUBORN (can be had for a price)

  5. Ambiguity Example – “Mary Had a Little Lamb” (Cont’d) • Lamb 1a: a young sheep esp. less than one year old or without permanent teeth . . . 1b: the young of various other animals (e.g., smaller antelopes) . . . 2a: a person as gentle or weak as a lamb . . . 2b: DEAR, PET . . . 2c: a person easily cheated or deceived, esp. in trading securities . . . 3a: the flesh of lamb used as food.

  6. Lambic Interpretations

  7. Techniques for Disambiguation • Memorization heuristic – Ask several individuals from both development and stakeholders to try to recall from memory the customer’s real requirement. Parts that cannot easily be remembered or are not clear are likely to be ambiguous. • Keyword technique – Identify the key operational words and look up the definitions. Then mix and match the definitions to determine different possible interpretations.

  8. Techniques for Disambiguation (Cont’d) • Emphasis technique – Read the requirement aloud and emphasize individual words until as many different interpretations as possible have been discovered. • Other techniques – If appropriate, use pictures or graphics to flush out any ambiguities.

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