The invariant rings of the Sylow groups of GU(3,q2), GU(4,q2), Sp(4,q) and O+(4,q) in the natural characteristic
文摘
Let m>Gm> be a Sylow m>p m>-subgroup of the unitary groups an id="mmlsi1" class="mathmlsrc">an class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0747717116000225&_mathId=si1.gif&_user=111111111&_pii=S0747717116000225&_rdoc=1&_issn=07477171&md5=dfd5516288f027b70f00888950a5ee08" title="Click to view the MathML source">GU(3,q2)an>an class="mathContainer hidden">an class="mathCode"><math altimg="si1.gif" overflow="scroll"><mi>Gmi><mi>Umi><mo stretchy="false">(mo><mn>3mn><mo>,mo><msup><mrow><mi>qmi>mrow><mrow><mn>2mn>mrow>msup><mo stretchy="false">)mo>math>an>an>an>, an id="mmlsi2" class="mathmlsrc">an class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0747717116000225&_mathId=si2.gif&_user=111111111&_pii=S0747717116000225&_rdoc=1&_issn=07477171&md5=8a87185a51c07ea0caa14f34e075c9aa" title="Click to view the MathML source">GU(4,q2)an>an class="mathContainer hidden">an class="mathCode"><math altimg="si2.gif" overflow="scroll"><mi>Gmi><mi>Umi><mo stretchy="false">(mo><mn>4mn><mo>,mo><msup><mrow><mi>qmi>mrow><mrow><mn>2mn>mrow>msup><mo stretchy="false">)mo>math>an>an>an>, the symplectic group an id="mmlsi3" class="mathmlsrc">an class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0747717116000225&_mathId=si3.gif&_user=111111111&_pii=S0747717116000225&_rdoc=1&_issn=07477171&md5=f91c5d9153a0ef685c0e38cdfd54ef53" title="Click to view the MathML source">Sp(4,q)an>an class="mathContainer hidden">an class="mathCode"><math altimg="si3.gif" overflow="scroll"><mi>Smi><mi>pmi><mo stretchy="false">(mo><mn>4mn><mo>,mo><mi>qmi><mo stretchy="false">)mo>math>an>an>an> and, for m>q m> odd, the orthogonal group an id="mmlsi4" class="mathmlsrc">an class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0747717116000225&_mathId=si4.gif&_user=111111111&_pii=S0747717116000225&_rdoc=1&_issn=07477171&md5=2baf6b4499905367b06a2063b755aba7" title="Click to view the MathML source">O+(4,q)an>an class="mathContainer hidden">an class="mathCode"><math altimg="si4.gif" overflow="scroll"><msup><mrow><mi>Omi>mrow><mrow><mo>+mo>mrow>msup><mo stretchy="false">(mo><mn>4mn><mo>,mo><mi>qmi><mo stretchy="false">)mo>math>an>an>an>. In this paper we construct a presentation for the invariant ring of m>Gm> acting on the natural module. In particular we prove that these rings are generated by orbit products of variables and certain invariant polynomials which are images under Steenrod operations, applied to the respective invariant form defining the corresponding classical group. We also show that these generators form a m>SAGBIm> basis and the invariant ring for m>Gm> is a complete intersection.