# Thread: Combinations Question

1. ## Combinations Question

I have required fields to fill in before somebody clicks submit in a computer program, but I want to tell our testing team that we need to test to make sure the program does not submit unless all required fields are filled in. But, I want to test all of the combinations of the required fields, except for the combination where I fill all the fields in because that should always work.

Is this expressed as

n choose (n-1), where n is the number of required fields?

If so, do you know if there is any software program we could use that will generate a true/false table of combinations if we supply the names of the variables to automate a list for us so that this can be printed out? It would have to be something free, but I just need a basic program.

Thanks

2. Hello applewine

Welcome to Math Help Forum!
Originally Posted by applewine
I have required fields to fill in before somebody clicks submit in a computer program, but I want to tell our testing team that we need to test to make sure the program does not submit unless all required fields are filled in. But, I want to test all of the combinations of the required fields, except for the combination where I fill all the fields in because that should always work.

Is this expressed as

n choose (n-1), where n is the number of required fields?
No. This assumes that all the required fields are filled in except 1. You need to test for $0, 1, ..., (n-1)$ fields filled in. The total number of possibilities is therefore
$\sum_{i=0}^{n-1}\binom ni = 2^n -1$
If so, do you know if there is any software program we could use that will generate a true/false table of combinations if we supply the names of the variables to automate a list for us so that this can be printed out? It would have to be something free, but I just need a basic program.

Thanks
No, I don't. Have you considered trying to set something up in Excel? It handles True/False values quite neatly, with Boolean operators AND, OR and NOT.