**MYBOOLEAN**
capture program drop myboolean
program define myboolean      
        // e.g. A, B, C, D to abcd ... ABCD       
        version 8 
        syntax varlist 
	  tokenize `varlist' 
        local nvars : word count `varlist'

        // i = 1, ..., 2^# variables
        qui forval i = 1/`=2 ^`: word count `varlist''' { 
                // binary representation of i - 1  
                inbase 2 `= `i' - 1' 
                local ibin : di %0`nvars'.0f `r(base)' 
                
                // initialise name and expression 
                local name 
                local exp "min(" 
                
                forval j = 1 / `nvars' { 
                        local char = substr("`ibin'",`j',1) 
                        if `char' { 
                                local name "`name'``j''" 
                                local exp  "`exp'``j''," 
                        }        
                        else {
                                local lcj = lower("``j''") 
                                local name "`name'`lcj'" 
                                local exp  "`exp'1-``j''," 
                        }        
                }
                
                // we have a trailing comma: as each arg is <= 1, 
                // closing with a 2 is safe 
                gen `name' = `exp'2) 
        }
end