For instance when the question contains $\{a,b\}^*$ does this mean that the DFA must have at least one $a$ and one $b$ on top of whatever conditions it has?
For example a DFA that accepts $\{w \in \{a,b\}^* : w \text{ contains } bbb\}$ should it reject the actual string $bbb$ because it does not contain an $a$?
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3$\begingroup$ What definition of $*$ do you use? $\endgroup$ – greybeard Feb 5 '20 at 8:39
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$\{a,b\}$ is set notation. The alphabet of a language is the set of all possible symbol used in the language. You can substitute the typical $\Sigma$ for the full set every time.
$\Sigma^*$ (where $^*$ is the kleene star) is the set of all possible strings you can make with that alphabet. That includes strings that happen to not use a certain character.
Therefor $\{w \in \{a,b\}^* : w \text{ contains } bbb\}$ is equivalent to $\{w \in \Sigma^* : \Sigma = \{a,b\} \text{ and } w \text{ contains } bbb\}$. But it skipped defining $\Sigma$ for terseness reasons.
