Llucasiewicz
Jan Llukasiewicz (1878-1956) proved that any algebraic expression with any
number of nested parentheses e.g. a*(b+c*d) can be re-written as a stack of
operators and operands - without any parentheses at all. He proposed two
equivalent forms: in his 'normal' Polish Notation operators are pushed in
the stack before operands e.g. *+*dcba; in the Inverse Polish Notation (used
in the inspired HP calculators) operands come first e.g. abcd and operators
come next *+*. By the way (further off topic) Llukasiewicz is considered by
many as the father of multivalued logic ( takes in to account 'grey' truth
values somewhere between 0 and 1) and therefore the founder of fuzzy sets
theory, fuzzy systems, fuzzy control etc.
I am sorry for this off-topic promenade - just couldn't help it...
George Chamilothoris
number of nested parentheses e.g. a*(b+c*d) can be re-written as a stack of
operators and operands - without any parentheses at all. He proposed two
equivalent forms: in his 'normal' Polish Notation operators are pushed in
the stack before operands e.g. *+*dcba; in the Inverse Polish Notation (used
in the inspired HP calculators) operands come first e.g. abcd and operators
come next *+*. By the way (further off topic) Llukasiewicz is considered by
many as the father of multivalued logic ( takes in to account 'grey' truth
values somewhere between 0 and 1) and therefore the founder of fuzzy sets
theory, fuzzy systems, fuzzy control etc.
I am sorry for this off-topic promenade - just couldn't help it...
George Chamilothoris