Checking conditional and mutual independence

[Aseem]

Hi,
I am working on bayesian networks and i am encountering problem in calculation of conditional and mutual independence.
My problem is
I have three variables(say variable1,variable2 and variable3)
variable1 can take three possible states viz. 1)low 2)normal 3)high
varable2 can take two possible states viz. 1)true 2)false
variable3 can take three possible states viz. 1)low 2)normal 3)high

i have 5000 instances of these three variables,i have to calculate

1)Mutual independence between variable1 and variable2. i.e. MI(var1,var2)
2)Conditional Independence of variable1 and variable2 given variable3 i.e. CI(var1,var2|var3)

please help...