Lecture 5-Algorithms, Turing Machines, & Universal Turing Machines

Question 1

What is a UTM?

Answer 1

A UTM is:
A TM which can simulate an arbitrary TM on an arbitrary input

Reads from its own tape:

• The definition of the TM being simulated
• The tape of the TM being simulated

Question 2

What are the uses of UTMs?

Answer 2

• The ultimate imitation game
• Can imitate any computer
• Virtual machines (VM), e.g. to run
  . Windows operating system on Linux,
  . Linux on Windows,
  . Android on Windows,
• Java Virtual Machine (JVM) – runs on any computer
• Interpreters …

Question 3

What is a Compiler?

Answer 3

Source code compiled machine code all at one time
Fast execution
Compiled for specific Machine
Machine code sold/distributed

Question 4

What is an Interpreter?

Answer 4

Source code compiled line by line
Slow execution
Can be run on any computer
Easier to debug
Source code is sold/distributed