Palindrome (; "again") and ' (; "way, direction"). Palindromes date back at least to 79 AD, as a palindrome was found as a graffito at Herculaneum, a city buried by ash in that year. This palindrome, called the Sator Square, consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas" ("The sower Arepo holds with effort the wheels"). It is remarkable for the fact that the first letters of each word form the first word, the second letters form the second word, and so forth. Hence, it can be arranged into a word square that reads in four different
Linear belief function discrete belief functions. Second, if a variable has zero variance, it will not permit a sweeping operation. In this case, we can pretend the variance to be an extremely small number, say ε, and perform the desired sweeping and combination. We can then apply a reverse sweeping to the combined matrix on the same variable and let ε approaches 0. Since zero variance means complete certainty about a variable, this ε-procedure will vanish ε terms in the final result. In general, to combine two linear belief functions, their moment matrices must be fully swept. However, one may combine a fully