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relation (X1, X2, X3, ... Xn) = (a11 a12 ... a1n)(x1, x2, ... xn) |a21 a22 ... a2n| | . . ... . | | . . ... . | |an1 an2 ... ann| that portion of the algebraic fraction, 1 ---------------------------------, (1 - s1X1)(1 - s2X2)...(1 - snXn) which is a function of the products s1x1, s2x2, s3x3, ... snxn only is 1 -------------------------------------------------------- |(1 - a11s1x1)(1 - a22s2x2)(1 - a33s3x3)(1 - ann.sn.xn)| where the denominator is in a symbolic form and denotes on expansion 1 - [Sigma]|a11|s1x1 + [Sigma]|a11a22|s1s2x1x2 - ... + (-)^n|a11a22a33...ann|s1s2 ... sn.x1x2...xn, where |a11|, |a11a22|, ... |a11a22,...ann| denote the several co-axial minors of the determinant |a11a22...ann| of the matrix. (For the proof of this theorem see MacMahon, "A certain Class of Generating Functions in the Theory of Numbers," _Phil. Trans. R. S._ vol. clxxxv. A, 1894). It follows that the coefficient of x1^[xi]1 x2^[xi]2 ... xn^[xi]n in the product (a11x1 + a12x2 + ... + a1n.xn )^[xi]^1 (a21x1 + a22x2 + ... + + a2n.xn)^[xi]^2...(an1x1 + an2x2 + ... + ann.xn)^[xi]n is equal to the coefficient of the same term in the expansion ascending-wise of the fraction 1 --------------------------------------------------------------------------. 1 - [Sigma]|a11|x1 + [Sigma]|a11a22|x1x2 - ... + (-)^n|a11a22...|x1x2...xn If the elements of the determinant be all of them equal to unity, we obtain the functions which enumerate the unrestricted permutations of the letters in x1^[xi]1 x2^[xi]2 ... xn^[xi]n, viz. (x1 + x2 + ... - xn)^{[xi]1 + [xi]2 + ... + [xi]n} 1 and ------------------------. 1 - (x1 + x2 + ... + xn) Suppose that we wish to find the generating function for the enumeration of those permutations of the letters in x1^[xi]1 x2^[xi]2...x3^[xi]n which are such that no letter xs is in a position originally occupied by an x3 for all values of s. This is a generalization of the "Probleme des rencontres" or of "derangements." We have merely to put a11 = a22 = a33 = ... = ann = 0 and the remaining elements equal to unity. The generating product is (x2 + x3 + ... + xn)^[xi]1 (x1 + x3 + ... + xn)^[xi]2 ... (x1 + x2 + ..
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