Formal Languages and Automata theory

Learn to construct a deterministic finite automaton that accepts exactly the length-two strings over {0,1}, using initial and final states to recognize 01 and reject other pairs.

Build a DFA for strings over {a,b} of length at least two, using an initial and final state with transitions on a and b to accept all long strings.

Construct a deterministic finite automaton over {a,b} that accepts all strings of length at most 2, including the empty string, by configuring final states for lengths 0, 1, and 2.

Design a deterministic finite automaton over the alphabet {a, b} that accepts all strings ending with abb, using a state-tracking approach for suffixes a, ab, and abb.

design a dfa that accepts all strings over {a,b} that start with abb by building a prefix chain and a final state with a self-loop for the remaining input.

Design a deterministic finite automaton over the alphabet {a, b} that accepts strings containing theSubstring abb.

Construct a DFA for strings whose length is divisible by 3 using three states for remainders 0, 1, and 2, with the initial and final state at remainder 0.

Design a dfa that accepts strings where the number of a's equals two, allowing any number of b's and transitioning to a dead state if more a's appear.

Construct a deterministic finite automaton with three states representing remainders 0, 1, and 2; transition on each a advances the remainder; accept when the remainder is 0.

This lecture explains building a four-state dfa to recognize strings over {a,b} with even numbers of a’s and b’s by tracking parity from the start in the even-even state.

Constructs a DFA to accept strings where a's are divisible by 3 and b's by 2, using a 3×2 state matrix with defined transitions and final states.

Explore how a three-state DFA reads binary input to decide divisibility by three, using remainders 0, 1, and 2, and accepting when the remainder is 0.

Construct a dfa that accepts all strings over {0,1} by using a single initial final state with self-loops on 0 and 1, so epsilon is accepted as well.

Explain how to design a deterministic finite automaton that accepts strings starting with a and ending with b, using states to enforce the initial a and final b.

Construct a DFA that accepts strings starting with a and ending with b, or starting with b and ending with a, using distinct state paths.

Build a DFA that recognizes strings not ending with ab by treating the ends-with-ab case as a base and deriving its complement, then determine accepting states through a transition table.

Design a DFA that accepts strings over {a, b} where every a is followed by b, with bs unconstrained.

Explore how a dfa recognizes the language a^n b^m with n,m >=1 by enforcing a's then nonempty b's, with no a after a b.

this lecture explains designing a dfa that accepts strings whose second symbol from the left is a, and uses final and nonfinal states with self-loops to handle the right-symbol case.

Design a DFA that recognizes strings of the form a^3 b w a^3, where w is any string. Starts with a^3, then b, then any w, and ends with a^3.

Learn how to build a dfa for the language a^n with n≥1 and n≠3, distinguishing lengths 0,1,2,3 and 4 plus to accept all valid lengths while rejecting 0 and 3.

Explore how to convert an e-NFA to an NFA by computing epsilon closures for each state and updating transitions to remove epsilon moves.

Learn how to minimize a DFA using the equivalence method by removing unreachable states and merging equivalent states to obtain a smaller automaton that preserves accepted strings.

Minimize a DFA with the table filling method by removing non-reachable states, filling a state-pair table to mark distinguishable pairs, then merging equivalent states to reduce the automaton.

Learn how to determine whether two DFAs recognize the same language by comparing their accepted and rejected strings through a joint state traversal; a mismatch in final status proves inequivalence.

This lecture introduces pushdown automata, a stack-based model that recognizes context-free languages, covering deterministic and non-deterministic variants and acceptance by final state or empty stack.

Construct a push down automaton that accepts a^n b^n with n≥1 by pushing a's and popping on b's, using the bottom symbol and acceptance by final state or empty stack.

Design a pushdown automaton that accepts strings where the number of a's equals the number of b's, using a bottom marker, push and pop rules, and epsilon transitions.

Demonstrates constructing a pushdown automaton for the language a^n b^n c with n>=1, using push and pop on a and b, and validating a final c with the stack top.

Construct a pushdown automaton that accepts the language wcwR by pushing symbols until the marker c and then popping to match the reverse.

Design a nondeterministic pushdown automaton for the language L = { wwR }, identifying the middle point without a separator by pushing and popping on the stack.

Construct a pushdown automaton that accepts a^n b^{2n} over {a,b} by pushing two symbols for each a and popping one symbol for each b, ensuring 2n pushes match 2n pops.

Develop a pushdown automaton that accepts a^n bbb a^n for n>=1 by pushing for each a, skipping three b's, then popping to match.

Design a pushdown automaton that accepts a^n b^n a^m with m,n ≥ 1 over {a,b}, by pushing a's, popping on b's, and handling trailing a^m with a stack pivot.

Turing machines are infinite-memory automata with a read-write head on a tape, performing state transitions and accepting by final states, more powerful than finite automata in the Chomsky hierarchy.

Design a Turing machine that accepts the language {0^n | n is divisible by 3}, including epsilon, using alphabet 0 and a three-state remainder scheme with transition diagrams and tables.

Construct a turing machine that accepts a^n b^n with n≥1, marking a as x and b as y, matching counts via left-right scans and using a transition diagram and table.

Design a Turing machine for the language w c w^R, where w ∈ {a,b}*, showing how to match first and last symbols and verify the reverse after c.

Construct a Turing machine that accepts the language l = ww^R, where w = (a+b)*, by illustrating the mirrored structure and matching symbols with blanks.