Propositional logic and first order logic textbook What are in your opinion some good propositional and first order logic textbooks (undergraduate level)?
I need one that focuses mainly on the aspects of logic related to computer science.
thanks in advance. 
 A: My favourite introductory book on mathematical logic is Robert S. Wolfe's  A Tour Through Mathematical Logic. Amazingly well written, it covers an extraordinary amount of material in both logic and set theory, complete with biographical vignettes and historical insights. There a deep discussion of first order logic, and it's place in metamathematical systems. It also has a wonderful introductory chapter on the theory of computation and its origins. This is the book I would recommend to any of my students if they asked me about logic.
After that, there are several more advanced texts that I like, particularly the ones by Shoenfield and the classic by my old teacher, Elliot Mendelson.
You can't go wrong with any of those.
A: The question as currently stated is a little vague, but I took a course on logic and theorem proving as it relates to computer science as an undergraduate, and the textbook, Huth and Ryan's "Logic in Computer Science" (which I see now has a second edition) was a reasonable textbook.
For a somewhat different value of "aspects of logic related to computer science," Pfenning's notes on from his undergraduate course on Constructive Logic are relatively complete and might be useful.
A: I'm surprised that no one has yet mentioned Boolos 'Computability and Logic'. The first 100 pages are pretty solid computability theory, and then follows Meta-logic, with an especially good précis on first-order logic that emphasizes the difference between a language, a theory, and logical/non-logical symbols. Worth a gander, especially if you're interested in CS related logic.
Robert Soare's 'Recursively Enumerable Sets and Degrees' is another good place to start for recursion theory, as well as general logic. His approach is very clear (if a little assuming that you're following everything at once) and the first 120pp are very informative on recursively enumerable sets (now usually called computably enumerable). But for undergraduates, I'd go with the Boolos...
Note of warning - Mendelson's book Introduction to Mathematical Logic I found confusing when starting out - this was confirmed by supervisors/colleagues.
I hope this helps!
A: A first course in logic by S. Hedman (OUP) is excellent.
A: For a discussion of logic textbooks, highly recommended:
Teach Yourself Logic 2016:A Study Guide
Peter Smith
Available online at http://www.logicmatters.net/tyl/
A: It depends on what you mean by "related to computer science". Undergraduate computer science "logic" books tend to focus more on computability, like


*

*Hopcroft and Ullman, Introduction to Automata Theory, Languages, and Computation

*Papadimitriou, Computational Complexity
Undergraduate mathematical "logic" books tend to focus on propositional logic and first-order logic but not things like computational complexity. One well-regarded book of that sort is


*

*Enderton, A Mathematical Introduction to Logic
That book does prove the unique readability (parsing) algorithm for propositional and first-order formulas. 
A: As a clear introduction to propositional and first order logic for the mathematically minded, I think Logic and Structure by Van Dalen is in a class of its own. The majority of the book is not particularly CS focused, but the beginnings of recursion theory are covered in the last chapter.
A: A very clear (and free) introductory textbook is A Problem Course in Mathematical Logic - "a freeware mathematics text by Stefan Bilaniuk" available as pdf, ps and Latex source on http://euclid.trentu.ca/math/sb/pcml/pcml.html:

A Problem Course in Mathematical Logic
  is intended to serve as the text for
  an introduction to mathematical logic
  for undergraduates with some
  mathematical sophistication. It
  supplies definitions, statements of
  results, and problems, along with some
  explanations, examples, and hints. The
  idea is for the students, individually
  or in groups, to learn the material by
  solving the problems and proving the
  results for themselves. The book
  should do as the text for a course
  taught using the modified
  Moore-method.
The material and its presentation are
  pretty stripped-down and it will
  probably be desirable for the
  instructor to supply further hints
  from time to time or to let the
  students consult other sources.
  Various concepts and and topics that
  are often covered in introductory
  mathematical logic or computability
  courses are given very short shrift or
  omitted entirely, among them normal
  forms, definability, and model theory.
Parts I and II, Propositional Logic
  and First-Order Logic respectively,
  cover the basics of these topics
  through the Soundness, Completeness,
  and Compactness Theorems, plus a
  little on applications of the
  Compactness Theorem. They could be
  used for a one-term course on these
  subjects. Part III, Computability,
  covers the basics of computability
  using Turing machines and recursive
  functions; it could be used as the
  basis of a one-term course. Part IV,
  Incompleteness, is concerned with
  proving the Gödel Incompleteness
  Theorems.

A: *

*The Logic Book by Merrie Bergmann, et al, used to be used to teach propositional logic and first-order predicate logic to philosophy undergraduates at University College London (UCL) and at the University of Oxford. It has a gentle learning curve, with lots of exercises, and a companion volume of selected answers.

*Mathematical Logic, Part I by Cori and Lascar used to be used to teach mathematics undergraduates at some of the University of London colleges, IIRC, though I forget which ones. It has a steeper learning curve, but again has plenty of exercises. With this book, the exercises are at the back, not in a separate volume.
A: Not quite a textbook, but a collection of historical projects about elementary logic and
related issues in discrete mathematics and computer science can be found at
www.cs.nmsu.edu/historical-projects
Click on the project "Deduction Through the Ages ..."
A: Though a little advanced, Logic for Applications by Nerode and Shore fits the bill.  (Google books) The book has an extensive treatment of propositional and first-order logic, with an emphasis on resolution as a proof method. Hilbert style systems are also discussed to some length, but natural deduction is lacking. I found that the Prolog related parts can be successfully skipped if necessary.
A: I don't understand what people usually mean when they say "aspects of some mathematical field related to computer science" (how they know what is really related to CS?), but if you really want to study or teach first order logic, then, in my opinion, there is old but still the best book for that -- Joseph Shoenfield's Mathematical logic.
