  Current sky surveys have been conducted very accurately in order to
understand our universe. One of the phenomena survey maps provide is
gravitational effect. Albert Einstein (1936) first discussed the possibilities
of gravitational lensing effects based on his theory of general relativity,
which might give us some information about cosmology. We often categorize the
effects by micro, weak, and strong lensing types. This paper focuses on the
strong gravitational lensing, especially the double-source plane lens systems.
It was recently recognized that the double lensing events can provide us with
another method for constraining the cosmological parameters. To get a general
idea of 'how many of these lensing events can be found', we set up a toy model,
then follow up with several Bayesian models in order to perform statistical
analysis with artificially drawn datasets. The results showed that the double
lenses are, in fact, promising objects to constrain the cosmological
parameters.
