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```656/556 2003 1w 04 Syntax
Assigned work due
Ex1.6.2b: Prove not(not p or not q) |- p and q using Natural
Deduction (Use book notation or course www site notation).
ch 1.3 ex1.7
Key terms
wff  ::= "well formed formula".
tree
subformula
priorities
Questions?

Exercises on parsing and syntax
parse some wffs

How I do syntax and other definitions
XBNF handout
wff  ::= atom   |  "(" "not" wff ")"  |  ..,
How far can  BNF stretch?
Syntax.
t::=E.
Abreviations.
t::=a_long_descriptive_name.
Descriptions.
t::T,  P(t).
Then t has type T and P(t) is true.
Definitions and logic.
t::=E.
Then E can substitute for t in any expression or wff.
In effect, the same as t::type(E), t=E.

Exercise on XBNF
http://www.csci.csusb.edu/dick/cs656/train.html

Assigned work:  Exercise 1e from Ex1.7 on page 43: draw and hand
in parse tree for: p -> (~q \/ (q -> p))

lab: look at
http://www.csci.csusb.edu/dick/maths/intro_ebnf.html
Write your XBNF exercise into a *.mth file
and convert to HTML and look at it.
If time look at paper "How far can EBNF stretch."
http://www.csci.csusb.edu/dick/papers/rjb96x.xbnf.html

next: Holiday on Monday
Class on Wednsday
Semantics

http://www.csci.csusb.edu/dick/cs656/class/05.html
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