Advanced Topics · Lesson 9 · Practice
Practice: Factor Avoidance
Every quiz type from this lesson. Start at difficulty 1 and work up; correct answers build your streak, and after a few attempts this page points you at your weakest quiz.
Avoidance DFA transitions
Difficulty 1
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In the avoidance DFA for 10, which state does state 0
(recording ε)
reach on reading 1? Use the pattern length for the sink ⊥.
Difficulty 2
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In the avoidance DFA for 0111, which state does state 1
(recording "0")
reach on reading 1? Use the pattern length for the sink ⊥.
Difficulty 3
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In the avoidance DFA for 0101, which state does state 3
(recording "010")
reach on reading 0? Use the pattern length for the sink ⊥.
Difficulty 4
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In the avoidance DFA for 01110, which state does state 2
(recording "01")
reach on reading 0? Use the pattern length for the sink ⊥.
Count words avoiding a pattern
Difficulty 1
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How many length-3 words over a 2-letter alphabet avoid 001?
Difficulty 2
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How many length-5 words over a 2-letter alphabet avoid 1101?
Difficulty 3
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How many length-6 words over a 3-letter alphabet avoid 11101?
Difficulty 4
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How many length-8 words over a 3-letter alphabet avoid 010100?