  Polar codes are a class of linear error correction codes which provably
attain channel capacity with infinite codeword lengths. Finite length polar
codes have been adopted into the 5th Generation 3GPP standard for New Radio,
though their native length is limited to powers of 2. Utilizing multiple
polarizing matrices increases the length flexibility of polar codes at the
expense of a more complicated decoding process. Successive cancellation (SC) is
the standard polar decoder and has time complexity $\mathcal{O}(N \log N)$ due
to its sequential nature. However, some patterns in the frozen set mirror
simple linear codes with low latency decoders, which allows for a significant
reduction in SC latency by pruning the decoding schedule. Such fast decoding
techniques have only previously been used for traditional Arikan polar codes,
causing multi-kernel polar codes to be an impractical length-compatibility
technique with no fast decoders available. We propose fast simplified
successive cancellation decoding node patterns, which are compatible with polar
codes constructed with both the Arikan and ternary kernels, and generalization
techniques. We outline efficient implementations, made possible by imposing
constraints on ternary node parameters. We show that fast decoding of
multi-kernel polar codes has at least 72% reduced latency compared with an SC
decoder in all cases considered where codeword lengths are (96, 432, 768,
2304).
