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I was going through section 9.2 of Peskin and Schroeder, and came across equation 9.16 which reads

[tex]\int\mathcal{D}\phi(x) = \int \mathcal{D}\phi_{1}({{\bf{x}}}) = \int \mathcal{D}\phi_{2}({{\bf{x}}}\)int_{\phi(x_{1}^{0},{\bf{x}})\\\phi(x_{1}^{0},{\bf{x}})}\mathcal{D}\phi(x)[/tex]

What does the right hand side mean, and how does this follow from

[tex]\int\mathcal{D}\phi(x) \phi(x_1)\phi(x_2)\exp{\left[i\int_{-T}^{T}d^{4}x \mathcal{L}(\phi)\right]}[/tex]

? What is the relationship between [itex]x_{1}^{0}[/itex] and [itex]T[/itex]?

Thanks in advance.

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# Correlation Functions in Path Integral Formulation of QFT

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