<p>For function germs <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(g:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}},0)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>g</mi> <mo>:</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">→</mo> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="double-struck">C</mi> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> it is well known that <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(1\le \frac{\mu (g)}{\tau (g)}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>≤</mo> <mfrac> <mrow> <mi>μ</mi> <mo stretchy="false">(</mo> <mi>g</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>τ</mi> <mo stretchy="false">(</mo> <mi>g</mi> <mo stretchy="false">)</mo> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> and it has recently been proved by Liu that <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\frac{\mu (g)}{\tau (g)}\le n\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mrow> <mi>μ</mi> <mo stretchy="false">(</mo> <mi>g</mi> <mo stretchy="false">)</mo> </mrow> <mrow> <mi>τ</mi> <mo stretchy="false">(</mo> <mi>g</mi> <mo stretchy="false">)</mo> </mrow> </mfrac> <mo>≤</mo> <mi>n</mi> </mrow> </math></EquationSource> </InlineEquation>. We give an upper bound for the codimension of map-germs <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(f:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}}^p,0)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>f</mi> <mo>:</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">→</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>p</mi> </msup> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> given as augmentations of other map-germs with which we prove the analog to the first inequality (known as the Mond conjecture) for augmentations <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(h:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}}^{n+1},0)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>h</mi> <mo>:</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mi>n</mi> </msup> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">→</mo> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mi mathvariant="double-struck">C</mi> </mrow> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </msup> <mo>,</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. Furthermore, we show that the quotient given by the image Milnor number and the codimension of any augmentation in the pair of dimensions <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\((n,n+1)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>,</mo> <mi>n</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is less than <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\frac{1}{4}(n+1)^2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mn>1</mn> <mn>4</mn> </mfrac> <msup> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> </mrow> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> and prove the analog to the second inequality for map-germs with <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(n=1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> and augmentations with <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(n=2,3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mn>2</mn> <mo>,</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation>. We then prove a characterization of when a map-germ is an augmentation, finding a counterexample for a characterization given by Houston. Next, we give sufficient conditions for when the augmentation is independent of the choice of stable unfolding by studying different notions of equivalence of unfoldings. Moreover, these results allow us to give sufficient conditions for the simplicity of an augmentation, providing context to locate the moduli for non-simple augmentations.</p>

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Augmentation of Singularities: \(\mu /\tau \)-type Conjectures and Simplicity

  • I. Breva Ribes,
  • R. Oset Sinha

摘要

For function germs \(g:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}},0)\) g : ( C n , 0 ) ( C , 0 ) it is well known that \(1\le \frac{\mu (g)}{\tau (g)}\) 1 μ ( g ) τ ( g ) and it has recently been proved by Liu that \(\frac{\mu (g)}{\tau (g)}\le n\) μ ( g ) τ ( g ) n . We give an upper bound for the codimension of map-germs \(f:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}}^p,0)\) f : ( C n , 0 ) ( C p , 0 ) given as augmentations of other map-germs with which we prove the analog to the first inequality (known as the Mond conjecture) for augmentations \(h:({\mathbb {C}}^n,0)\rightarrow ({\mathbb {C}}^{n+1},0)\) h : ( C n , 0 ) ( C n + 1 , 0 ) . Furthermore, we show that the quotient given by the image Milnor number and the codimension of any augmentation in the pair of dimensions \((n,n+1)\) ( n , n + 1 ) is less than \(\frac{1}{4}(n+1)^2\) 1 4 ( n + 1 ) 2 and prove the analog to the second inequality for map-germs with \(n=1\) n = 1 and augmentations with \(n=2,3\) n = 2 , 3 . We then prove a characterization of when a map-germ is an augmentation, finding a counterexample for a characterization given by Houston. Next, we give sufficient conditions for when the augmentation is independent of the choice of stable unfolding by studying different notions of equivalence of unfoldings. Moreover, these results allow us to give sufficient conditions for the simplicity of an augmentation, providing context to locate the moduli for non-simple augmentations.