  The planet occurrence rate for multiple stars is important in two aspects.
First, almost half of stellar systems in the solar neighborhood are multiple
systems. Second, the comparison of the planet occurrence rate for multiple
stars to that for single stars sheds light on the influence of stellar
multiplicity on planet formation and evolution. We developed a method of
distinguishing planet occurrence rates for single and multiple stars. From a
sample of 138 bright (KP <13.5) Kepler multi-planet candidate systems, we
compared the stellar multiplicity rate of these planet host stars to that of
field stars. Using dynamical stability analyses and archival Doppler
measurements, we find that the stellar multiplicity rate of planet host stars
is significantly lower than field stars for semi-major axes less than 20 AU,
suggesting that planet formation and evolution are suppressed by the presence
of a close-in companion star at these separations. The influence of stellar
multiplicity at larger separations is uncertain because of search in-
completeness due to a limited Doppler observation time baseline and a lack of
high resolution imaging observation. We calculated the planet confidence for
the sample of mutlti-planet candidates, and find that the planet confidences
for KOI 82.01, KOI 115.01, KOI 282.01 and KOI 1781.02 are higher than 99.7% and
thus validate the planetary nature of these four planet candidates. This sample
of bright Kepler multi-planet candidates with refined stellar and orbital
parameters, planet confidence estimation, and nearby stellar companion
identification offers a well-characterized sample for future theoretical and
observational study.
