= Validation, credit, and replication =

A computational result consists of:

 * The result itself (the output files)
 * The amount of CPU time used; this may be used to determine how much credit to grant for the result.

In general, neither of these can be trusted:

 * Some hosts have hardware problems (consistent or sporadic) that cause errors (usually in floating-point computation).
 * Some volunteers may maliciously return wrong results; they may even reverse-engineer your application, deciphering and defeating any sort of internal validation mechanism you might include in it.
 * Some volunteers may return correct results but falsify the CPU time.

There are
		purposes: correct results, correct credit
		no redundancy
			(still can validate)
			may bound credit
		redundancy
			exact match
				exact computation
					sixtrack example: compiler,
						compiler options (disable DP hardware),
						numerical libraries
				homogeneous redundancy
				exact checkpointing
			fuzzy matching