In computing, Physical Address Extension (PAE), sometimes referred to as Page Address Extension, is a memory management feature for the IA-32 architecture. PAE was first introduced in the Pentium Pro. It defines a page table hierarchy of three levels, with table entries of 64 bits each instead of 32, allowing these CPUs to access a physical address space larger than 4 gigabytes (232 bytes). The page table structure used by x86-64 CPUs when operating in 64-bit mode further extends the page table hierarchy to four levels, extending the virtual address space, and uses additional physical address bits...

Bayesian poisoning is a technique used by e-mail spammers to attempt to degrade the effectiveness of spam filters that rely on Bayesian spam filtering. Bayesian filtering relies on Bayesian probability to determine whether an incoming mail is spam or is not spam. The spammer hopes that the addition of random (or even carefully selected) words that are unlikely to appear in a spam message will cause the spam filter to believe the message to be legitimate—a statistical type II error. Spammers also hope to cause the spam filter to have a higher false positive rate by turning previously innocent words...