Consider the sentence in the abstract of the paper at https://arxiv.org/abs/1610.09038.

Empirically we find that Professor Forcing acts as a regularizer, improving test likelihood on character level Penn Treebank and sequential MNIST.

I have used MNIST dataset. However, I could not find any Sequential MNIST or permuted MNIST datasets.

Are they standard datasets published anywhere or I can just permute by myself and call them permuted while the standard one is just called the Sequential one.

I guess the distinction in papers (of using the two versions -- permuted and sequential MNIST) must be due to some reason, what could be the reason? Is it some transfer learning thing?

  • 2
    $\begingroup$ Read section 4.3. $\endgroup$
    – Batman
    Commented Jan 8, 2017 at 2:12

2 Answers 2


As in comment by @Batman, sequential MNIST is explained in section 4.3 of your link: https://arxiv.org/abs/1610.09038.

We evaluated Professor Forcing on the task of sequentially generating the pixels in MNIST digits.

As far as I am aware, sequential MNIST always implies the model does not get to see/generate the whole image at once (like for example a normal 2d-ConvNet would), but only one pixel at a time sequentially. So sequential MNIST should have the same meaning also in other non-generative contexts.

Also in section 4.3. they explain permuted mnist:

Applying a fixed random permutation to the pixels makes the problem even harder but IRNNs on the permuted pixels are still better than LSTMs on the non-permuted pixels.

The problem should be harder after permuting the pixels in all images with the same permutation, because you have to learn more long-range patterns: Distinctive shapes, like the horizontal bar of the 7 are typically more spread apart in the input after permutation compared to before.


Permutated Sequential MNIST is introduced in the "A Simple Way to Initialize Recurrent Networks of Rectified Linear Units" paper from 2015 which has Hinton as a co-author.

Sequential MNIST: "classify the MNIST digits [21] when the 784 pixels are presented sequentially to the recurrent net"

Permutated Sequential MNIST: same thing with "a fixed random permutation of the pixels of the MNIST digits"

Permutated Sequential MNIST is not a real dataset, it's just a transformation of the MNIST dataset to evaluate recurrent neural networks.


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