Why the out_channels of conv kernel must be 1?

[jackiechen0708]

Why the out_channels of conv kernel must be 1?
https://github.com/dstamoulis/single-path-nas/blob/b7c1310ef0056eb6063f9e79e000be069b01518d/nas-search/superkernel.py#L95

[amyburden]

it is depthwise conv with multiplier=1