maths
posted by bilish .
what are magic squares?
what is mathematical logic?

Since this is not my area of expertise, I searched Google under the key words "mathematical logic" to get these possible sources:
http://en.wikipedia.org/wiki/Mathematical_logic
http://www.math.psu.edu/simpson/courses/math557/logic.pdf
You can do the same under "math magic squares".
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps. Thanks for asking. 
ahhh, magic squares, one of my favourite topics in recreational math
they have been known for hundreds of years,
Antonio Gaudi incorporated a 4x4 magic square in his famous basilica in Barcelona
http://www.pballew.net/magsquar.html
and Albrecht Duerer had a differengt 4x4 in one of his illustrations
http://wwwgroups.dcs.stand.ac.uk/~history/Diagrams/Melancholia.jpeg
http://wwwgroups.dcs.stand.ac.uk/~history/Diagrams/Durers_square.jpeg