<p>In this paper, interpretations of wedge products of the geometric Segre, respectively, geometric Chern, forms of a holomorphic vector bundle <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(\,E\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>E</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> (with hermitian metric <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\,|\;\;|\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mo stretchy="false">|</mo> <mspace width="0.277778em" /> <mspace width="0.277778em" /> <mo stretchy="false">|</mo> </mrow> </math></EquationSource> </InlineEquation>) over a complex space <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\,Y\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>Y</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> are given by showing that: (a) the geometric Segre forms of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\,E\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>E</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> coincide with the Segre forms constructed by means of the Chern–Weil theory, in Sect.&#xa0;<InternalRef RefID="Sec6">6</InternalRef>; (b) as current the Segre wedge product <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\,\widehat{s}_1(E_{\infty };|\;\;|)^{\beta _1}\wedge \cdots \wedge \widehat{s}_{p+1}(E_{\infty };|\;\;|)^{\beta _{p+1}},\,\beta _j \in {\mathbb {Z}}[0,\infty ),\,p\in {\mathbb {N}}\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <msub> <mover accent="true"> <mi>s</mi> <mo stretchy="false">^</mo> </mover> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> </mrow> <msub> <mi>E</mi> <mi>∞</mi> </msub> <msup> <mrow> <mo>;</mo> <mo stretchy="false">|</mo> <mspace width="0.277778em" /> <mspace width="0.277778em" /> <mo stretchy="false">|</mo> <mo stretchy="false">)</mo> </mrow> <msub> <mi>β</mi> <mn>1</mn> </msub> </msup> <mo>∧</mo> <mo>⋯</mo> <mo>∧</mo> <msub> <mover accent="true"> <mi>s</mi> <mo stretchy="false">^</mo> </mover> <mrow> <mi>p</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> <mrow> <mo stretchy="false">(</mo> </mrow> <msub> <mi>E</mi> <mi>∞</mi> </msub> <msup> <mrow> <mo>;</mo> <mo stretchy="false">|</mo> <mspace width="0.277778em" /> <mspace width="0.277778em" /> <mo stretchy="false">|</mo> <mo stretchy="false">)</mo> </mrow> <msub> <mi>β</mi> <mrow> <mi>p</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> </msup> <mo>,</mo> <mspace width="0.166667em" /> <msub> <mi>β</mi> <mi>j</mi> </msub> <mo>∈</mo> <mi mathvariant="double-struck">Z</mi> <mrow> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <mspace width="0.166667em" /> <mi>p</mi> <mo>∈</mo> <mi mathvariant="double-struck">N</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> is extendible to a generalized Schubert cycle on <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\,Y,\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>Y</mi> <mo>,</mo> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> provided <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\,E\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>E</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> is semi-globally spanned, in Sect.&#xa0;<InternalRef RefID="Sec7">7</InternalRef>; (c) the cup product <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\,(-1)^{w(\beta )}\widehat{s}_1(E)^{\beta _1}\cup \cdots \cup \widehat{s}_{p+1}(E)^{\beta _{p+1}},\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <msup> <mrow> <mo stretchy="false">(</mo> <mo>-</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>w</mi> <mo stretchy="false">(</mo> <mi>β</mi> <mo stretchy="false">)</mo> </mrow> </msup> <msub> <mover accent="true"> <mi>s</mi> <mo stretchy="false">^</mo> </mover> <mn>1</mn> </msub> <msup> <mrow> <mo stretchy="false">(</mo> <mi>E</mi> <mo stretchy="false">)</mo> </mrow> <msub> <mi>β</mi> <mn>1</mn> </msub> </msup> <mo>∪</mo> <mo>⋯</mo> <mo>∪</mo> <msub> <mover accent="true"> <mi>s</mi> <mo stretchy="false">^</mo> </mover> <mrow> <mi>p</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> <msup> <mrow> <mo stretchy="false">(</mo> <mi>E</mi> <mo stretchy="false">)</mo> </mrow> <msub> <mi>β</mi> <mrow> <mi>p</mi> <mo>+</mo> <mn>1</mn> </mrow> </msub> </msup> <mo>,</mo> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> if non-vanishing, is equal to the fundamental class of an analytic intersection cycle supported by a Schubert type analytic set, provided <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\,E\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>E</mi> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation> is globally spanned, in Sect.&#xa0;<InternalRef RefID="Sec8">8</InternalRef>; and (d) similar results hold for the geometric Chern forms and the (analogously defined) Chern wedge products. As prerequisites multi-symbol Schubert type analytic sets and the (corresponding) Chern–Cowen forms are first introduced for a semi-globally spanned vector bundle <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\,E\rightarrow Y.\,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mspace width="0.166667em" /> <mi>E</mi> <mo stretchy="false">→</mo> <mi>Y</mi> <mo>.</mo> <mspace width="0.166667em" /> </mrow> </math></EquationSource> </InlineEquation></p>

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On the geometric Segre and Chern classes of vector bundles and generalized Schubert cycles

  • Chia-Chi Tung

摘要

In this paper, interpretations of wedge products of the geometric Segre, respectively, geometric Chern, forms of a holomorphic vector bundle \(\,E\,\) E (with hermitian metric \(\,|\;\;|\) | | ) over a complex space \(\,Y\,\) Y are given by showing that: (a) the geometric Segre forms of \(\,E\,\) E coincide with the Segre forms constructed by means of the Chern–Weil theory, in Sect. 6; (b) as current the Segre wedge product \(\,\widehat{s}_1(E_{\infty };|\;\;|)^{\beta _1}\wedge \cdots \wedge \widehat{s}_{p+1}(E_{\infty };|\;\;|)^{\beta _{p+1}},\,\beta _j \in {\mathbb {Z}}[0,\infty ),\,p\in {\mathbb {N}}\,\) s ^ 1 ( E ; | | ) β 1 s ^ p + 1 ( E ; | | ) β p + 1 , β j Z [ 0 , ) , p N is extendible to a generalized Schubert cycle on \(\,Y,\,\) Y , provided \(\,E\,\) E is semi-globally spanned, in Sect. 7; (c) the cup product \(\,(-1)^{w(\beta )}\widehat{s}_1(E)^{\beta _1}\cup \cdots \cup \widehat{s}_{p+1}(E)^{\beta _{p+1}},\,\) ( - 1 ) w ( β ) s ^ 1 ( E ) β 1 s ^ p + 1 ( E ) β p + 1 , if non-vanishing, is equal to the fundamental class of an analytic intersection cycle supported by a Schubert type analytic set, provided \(\,E\,\) E is globally spanned, in Sect. 8; and (d) similar results hold for the geometric Chern forms and the (analogously defined) Chern wedge products. As prerequisites multi-symbol Schubert type analytic sets and the (corresponding) Chern–Cowen forms are first introduced for a semi-globally spanned vector bundle \(\,E\rightarrow Y.\,\) E Y .