Abstract
We show that every function of several variables on a finite set of k elements with n > k essential variables has a variable identification minor with at least n -k essential variables. This is a generalization of a theorem of Salomaa on the essential variables of Boolean functions. We also strengthen Salomaa's theorem by characterizing all the Boolean functions f having a variable identification minor that has just one essential variable less than f.
Original language | British English |
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Pages (from-to) | 975-986 |
Number of pages | 12 |
Journal | International Journal of Foundations of Computer Science |
Volume | 18 |
Issue number | 5 |
DOIs | |
State | Published - Oct 2007 |
Keywords
- Arity gap
- Boolean functions
- Essential variables
- Functions on finite sets
- Minors of functions
- Variable identification