CIS301 Announcements

May 3

Exam 3 is scheduled for Tuesday, May 12, 11:50am, in the classroom. There are no more lectures this term.

March 27

Exam 2 is scheduled for Weds. April 1. There is no class on Friday April 3 and Monday April 6.

February 2

There is no lecture on February 4. Mr. Hoag will conduct class on February 6. It appears we will have our first in-class exam on Friday, Feb. 13. (More to come...)

January 30

The python programming language uses indentation to remember the structure of loops, conditional commands, and sequences of assignments. For this reason, the checker is programmed to enforce correct indentation. You must indent the first line of every proof you write so that it is indented the same amount as the command it follows. Please see the examples from the lectures. (If you do not indent correctly, the checker will complain and get lost.)

January 29

Some people have noted that the examples in the ``Smart'' (''S'') version of the lecture notes do not match the input syntax for the proof-checker tool. This is true --- please see the examples in the ''Text'' (''T'') version of the lecture notes to see how the examples should be typed in the checker.

January 28

Please submit your answers to Assignment 2 via K-State Online. You can submit them as a single text file or as a zipped folder. The assignment must be submitted by 7pm on Friday, Jan. 30.

I will be in my office on Thurs. Jan 29, from 3pm-4:30pm, and on Fri. Jan. 30, from 1:30pm-3:30pm, to answer any questions you may have.

January 26

Please read the tutorial page at http://people.cis.ksu.edu/~schmidt/301s09/howtocheck before you use the checker tool for the next Exercise set. In particular, please note that

It is important that you fully parenthesize nested arithmetic and logical expressions. That is, write
```
x = 2 + (3 * 4)
```
and not x = 2 + 3 * 4. And similarly, write
```
1.  (x == 2 or x == 3) or x == 4    premise
```
and not x == 2 or x == 3 or x == 4. The checker does not apply default precedences!
The checker does not know how to reason about division or modulo or fractional numbers (just yet), so don't use these.
The checker cannot handle strings just yet (except within print commands).
The checker's algebra solver does poorly with polynomials, so do not expect to use the algebra justification to prove all numerical facts. For example, the checker is unable to validate
```
x = readInt()
assert x > 1
"""{ 1. x > 1   premise
     2. x * x > x   algebra 1
}"""
```
because it has trouble comparing quadratic terms with linear ones. (It does better with equality expressions, however.) Often, you can carefully apply the subst justification to prove what you want when you work with quadratics.

January 22

Please bring your solutions to Exercise Set 1, written or printed on paper, to class on the 23rd. Future exercise sets will be submitted to K-State Online, and I will have more to say about this next week....