Define a two-headed finite automaton (2DFA) to be a deterministic finite automaton that has two read-only, bidirectional heads that start at the left-hand end of the input tape and can be independently controlled to move in either direction. The tape of a 2DFA is finite and is just large enough to contain the input plus two additional blank tape cells, one on the left-hand end and one on the right-hand end, that serve as delimiters. A 2DFA accepts its input by entering a special accept state. For example, a 2DFA can recognize the language (anbncn l n >= 0). a. Let A2DFA= { | M is a 2DFA and M accept x}. Show that A2DFA is decidable.
b. Let E2DFA= { | M is a 2DFA and L(M)= ϕ}. Show that E2DFA is decidable.

1.the index finger on your right hand types the f r v 4 j u m 7 h y 6 n lo.9 j u 7 m g t 5 b 2.if you need to multiply 400, 2, and 1 ½, what would you type on the numeric keypad? 400*2*1.5 400/2*1.5 400/2/1.5 400*2*1½ 3.select all examples of proper keyboarding technique. rest your fingers gently on the home row or home keys. slouch in your chair. rest your palms on the keyboard. relax your fingers. keep your hands lower than your elbows.

Your computer running windows 10 is doing some very strange things with the operating system. you are fairly certain it is not a hardware issue. you need to try to get further insight into what is going on within the operating system. which tool would be best suited for this?

When you type the pwd command, you notice that your current location on the linux filesystem is the /usr/local directory. answer the following questions, assuming that your current directory is /usr/local for each question. a. which command could you use to change to the /usr directory using an absolute pathname? b. which command could you use to change to the /usr directory using a relative pathname? c. which command could you use to change to the /usr/local/share/info directory using an absolute pathname? d. which command could you use to change to the /usr/local/share/info directory using a relative pathname? e. which command could you use to change to the /etc directory using an absolute pathname? f. which command could you use to change to the /etc directory using a relative pathname?