ScalingStacks

Definition 2.9 . [03N2]

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Definition 2.9.

A closed Lagrangian LL in ℂm{\mathbin{\mathbb{C}}}^{m} is called an LMCF expander if H=α​F⟂H=\alpha F^{\perp} in C∞(Tℂm|L)C^{\infty}(T{\mathbin{\mathbb{C}}}^{m}|_{L}), where HH is the mean curvature of LL and F⟂F^{\perp} is the orthogonal projection of the position vector FF (that is, the inclusion F:L↪ℂmF:L\hookrightarrow{\mathbin{\mathbb{C}}}^{m}) to the normal bundle TL⟂⊂Tℂm|LTL^{\perp}\subset T{\mathbin{\mathbb{C}}}^{m}|_{L}, and α>0\alpha>0 is constant.

This implies that (after reparametrizing by diffeomorphisms of LL) the family of Lagrangians Lt:=2​α​t​LL^{t}:=\sqrt{2\alpha t}\,L for t∈(0,∞)t\in(0,\infty) satisfy Lagrangian mean curvature flow. That is, Lagrangian MCF expands LL by dilations.

Similarly, we call LL an LMCF shrinker if H=α​F⟂H=\alpha F^{\perp} for α<0\alpha<0, and then Lt:=2​α​t​LL^{t}:=\sqrt{2\alpha t}\,L for t∈(−∞,0)t\in(-\infty,0) satisfy LMCF, so LMCF shrinks LL by dilations.

We call LL an LMCF translator if H=v⟂H=v^{\perp}, where v∈ℂmv\in{\mathbin{\mathbb{C}}}^{m} is the translating vector of LL, and v⟂v^{\perp} the orthogonal projection of vv to T​L⟂TL^{\perp}. Then Lt:=L+t​vL^{t}:=L+tv for t∈ℝt\in{\mathbin{\mathbb{R}}} satisfy LMCF, so Lagrangian MCF translates LL in ℂm{\mathbin{\mathbb{C}}}^{m}.

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