lispdoc  results for mean 
(alexandria.0.dev:mean sample)  Function: Returns the mean of SAMPLE. SAMPLE must be a sequence of numbers.

(min number &rest morenumbers)  Function: Return the least of its arguments; among EQUALP least, return the first.

Example:(defun cfand (a b) "Combine the certainty factors for the formula (A and B)." (min a b))  Mentioned in: CLtL2  12.3. Comparisons on Numbers CLtL2  28.1.7.4. Builtin Method Combination Types HyperSpec  Function MAX, MIN On Lisp  Applications for Macros PCL  inverse chi square PCL  numeric comparisons PCL  other method combinations 
minus  
Mentioned in: HyperSpec  2.4.8.18 Sharpsign Minus  
By Bill Moorier 