# History of Some Major Works to the Klein-Gordon equations

Nonlinear Klein-Gordon Equation(NLKG) 의 역사(?)를 간단히 정리해 보았습니다. 방정식 자체의 역사는 길지 몰라도, 방정식을 “수학적인 방법”으로 공략해서 성과를 얻어낸 역사는 생각보다 그리 길지 않습니다. 구체적으로 다음과 같은 형태의 NLKG의 역사에 대해 알아보겠습니다. (\square +1) u = F(u, \partial u),\;\;\;t\geqslant 0, … Continue reading

# [M1 Seminar II] Week 8 : Lorentz Invariance of the Wave Equations

Now we will introduce some lemmas for the proof of the global existence theorem for the nonlinear wave equations with quadratic nonlinearities. The exsistence theorem which was proven before gives $n >5$ for the quadratic nonlinearities. But in fact this … Continue reading

# [M1 Seminar II] Week 7 : A Global Existence Theorem for Nonlinear Wave Equations

We consider the following initial value problem $y_{tt} – \Delta y = f(Dy,\nabla Dy)\;\;\;\;\text{with}\;\;\;\; y(t=0) = y_0,\; y_t (t=0) = y_1 \tag{P}$ with $f \in C^\infty ( \Bbb R^{(n+1)^2}, \Bbb R)$, $\exists \alpha \in \Bbb N$ such that … Continue reading