| − | \mathcal{L}_{CBOW} = log\sigma(\mathbf{v}^\top_{w_t} \mathbf{h}) + \sum^{k}_{i=1}log\sigma(-\mathbf{v}^\top_{w'_{o_i}} \mathbf{h}) | + | \mathcal{L}_{CBOW} = \log\sigma(\mathbf{v}^\top_{w_t} \mathbf{h}) + \sum^{k}_{i=1}\log\sigma(-\mathbf{v}^\top_{w'_{o_i}} \mathbf{h}) |