Decompositions matrices for unipotent blocks of classical groups of low rank Data provided by Gunter Malle. These data can be read with GAP by gap DecMat.g or with gap> Read("DecMat.g"); in a running GAP (works with version of GAP 3 distributed by Jean Michel and with GAP 4). The data are stored in the record DECMATS. Try gap> RecFields(DECMATS); (or RecNames(DECMATS) in GAP 4) to see which cases are available. Example: gap> DECMATS.B2d2; rec( blocklabels := [ 1, 1, 1, 2, 1, 1 ], blocks := [ [ "A0", "1", 2 ], [ "B2", "1.1", 0 ] ], condition := "??", d := 2, decmat := [ [ 1, 0, 0, 0, 0, 0 ], [ 1, 1, 0, 0, 0, 0 ], [ 1, 0, 1, 0, 0, 0 ], [ 0, 0, 0, 1, 0, 0 ], [ 0, 0, 0, 0, 1, 0 ], [ 1, 1, 1, 0, 2, 1 ] ], hc_series := [ "ps", "A1", "B1", "ps", "B2", ".1^2" ], name := [ "B", 2 ], ordinary := [ "2.", "11.", ".2", "1.1", "B2", ".11" ], origin := "Okuyama-Waki (1998)" ) The decomposition matrix in in .decmat, rows correspond to ordinary characters labeled as shown in .ordinary. Block distribution is in .blocklabels. The entry .hc_series shows the Harish-Chandra series of the characters corresponding the columns of the decomposition matrix. In GAP 4 the data can be nicely read by Browse( DECMATS.B2d2 ); or just the restriction to block number 1 by Browse( DECMATS.B2d2, 1 );