Re: [xacml] re: functions

[Polar Humenn <polar@syr.edu>]

These are my current text for the logical functions:

or

This function returns false if it has no arguments and returns true if one
of its arguments evaluates to true. The order of evaluation is
unspecified. The expression results in ERROR if at least one argument
results in ERROR and all other arguments result in ERROR or false.

and

This function returns true if it has no arguments and returns false if one
of its arguments evaluates to false. The order of evaluation is
unspecified. The expression results in ERROR if at least one argument
results in ERROR and all other arguments result in ERROR or true.

n-of

The first argument to this function is an xs:integer specifying the number
of the remaining arguments that are required to evaluate to true for the
expression to be considered true.  If the first argument is 0, the result
is true. If number of arguments after the first one is less than the value
of the first argument, the expression is considered to result in ERROR.
The order of evaluation is to first evaluate the integer value, then
evaluate the subsequent arguments. The order of the evaluation of the
subsequent arguments is unspecified. The expression only returns ERROR if
the required number of true values can only be reached if the number of
ERROR values were considered true.

Formally, assume the number of required true values is denoted by N, the
number of subsequent boolean arguments is denoted by A, and during the
evaluation, the number of false values is denoted by F, the number of true
values is denoted by T, and the number of errors is denoted by E, such
that A=(T+F+E). The following evaluation semantics shall hold:

	A < N, 			ERROR
	N <= T,			true
	T < N and N <= T+E, 	ERROR
	otherwise,		false