Hopefully this is not a duplicateHow do I prove a Language L={a,b,c} is decidable or notI read somewhere that if a turing machine accepts a language and halts on every input string then the language is decidable.Having said that how do i design / prove that a turing machine accepts {a b c}I am new to concepts of automata and compelexity so please don't kill me if this is too basic for a question
how to prove a language is decidable
decision problem
By definition, a language is decidable if there exists a Turing machine that accepts it, that is, halts on all inputs, and answers Yes on words in the language, No on words not in the language. Therefore one way of showing that a language is decidable is by describing a Turing machine that accepts it.There are many offline and online resources on Turing machines. For example, here are some introductory slides on Turing machines: part 1, part 2.