This pattern is available in the Spring 2016 issue of Cast-On Magazine, and will be available for individual pdf download in the spring of 2017.
The sleeves and bottom are knit separately, from the bottom up to the underarm where they are joined and worked together with the yoke. The yoke is shaped by working a few decrease rounds. A keyhole is worked in the upper part of the yoke by changing to rows, the rejoining to working in rounds at the neck. The underarm stitches are returned to the dpn’s and are joined using a three-needle bind off. This is a completely seamless sweater! No sewing required!