By J. L. Alperin

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Topics in Computational Algebra

The most function of those lectures is first to in brief survey the elemental con­ nection among the illustration conception of the symmetric team Sn and the idea of symmetric capabilities and moment to teach how combinatorial equipment that come up obviously within the thought of symmetric capabilities bring about effective algorithms to specific numerous prod­ ucts of representations of Sn by way of sums of irreducible representations.

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Example text

25: 0 1 ! 1 1 1 1 1 C = t2 − t1 , (b) det B (a) det @ t1 t2 t3 A = (t2 − t1 )(t3 − t1 )(t3 − t2 ), t1 t2 2 2 2 t1 t2 t3 1 0 1 1 1 1 C Bt B 1 t2 t3 t4 C C (c) det B B t2 t2 t2 t2 C = (t2 − t1 )(t3 − t1 )(t3 − t2 )(t4 − t1 )(t4 − t2 )(t4 − t3 ). 29. 22. (a) By direct substitution: pd − bq aq − pc pd − bq aq − pc ax + by = a +b = p, cx + dy = c +d = q. ad − bc ad − bc ad − bc ad − bc ! 2; 0 2 4 0 10 10 ! 1 5 7 1 4 −2 1 4 det det = , y= =− . (ii) x = −2 6 3 −2 12 3 12 6 (c) Proof by direct0substitution, expanding all the determinants.

V1 (x, y) v2 (x, y) ! w1 (x, y) w2 (x, y) ! Distributivity: (c + d) " ! v1 (x, y) v2 (x, y) ! # (c + d) v1 (x, y) (c + d) v2 (x, y) ! =c ! v1 (x, y) v2 (x, y) ! +d ! # ! v1 (x, y) c d v1 (x, y) v1 (x, y) c d = = (c d) . v2 (x, y) c d v2 (x, y) v2 (x, y) Unit for Scalar Multiplication: ! v1 (x, y) v1 (x, y) . = 1 v2 (x, y) v2 (x, y) ! , w1 (x, y) w2 (x, y) ! 9. We identify each sample value with the matrix entry mij = f (i h, j k). In this way, every sampled function corresponds to a uniquely determined m × n matrix and conversely.

B) span { ex , e3 x }; (c) 2. 12. Each is a solution, and the general solution u(x) = c1 + c2 cos x + c3 sin x is a linear combination of the three independent solutions. 13. (a) e2 x ; (b) cos 2 x, sin 2 x; (c) e3 x , 1; (d) e− x , e− 3 x ; (e) e− x/2 cos 23 x, √ √ √ √ √ x x x x e− x/2 sin 23 x; (f ) e5 x , 1, x; (g) ex/ 2 cos √ , ex/ 2 sin √ , e− x/ 2 cos √ , e− x/ 2 sin √ . 14. (a) If u1 and u2 are solutions, so is u = c1 u1 + c2 u2 since u + 4 u = c1 (u1 + 4 u1 ) + c2 (u2 + 4 u2 ) = 0, u(0) = c1 u1 (0) + c2 u2 (0) = 0, u(π) = c1 u1 (π) + c2 u2 (π) = 0.