modifications to validation. now always enforces the max number of variable. Neff was interested in allowing more variables so i upped the max to 13. added in a variable for enforcing the max variables so one small change can turn it on or off. a note on program capabilities. the program can handle up to 26 variables (all the alphabet), however a 26 variable expression has 67108864 lines in the table, and memory is lacking to hold that many lines. also each new variable roughly doubles the time required to generate tables.