This paper considers investment methods with deep learning in neural networks. In particular, as one can create various investment strategies by different specifications of a loss function, the current work presents two examples based on return anomalies detected by supervised deep learning (SL) or profit maximization by deep reinforcement learning (RL). It also applies learning of individual asset return dynamics to portfolio strategies.

Moreover, an empirical study shows that the investment performance are quite sensitive to exogenously specified items such as frequency of input data (e.g.monthly or daily returns), selection of a learning method, update of learning, number of layers in a network and number of units in intermediate layers. Especially, it is observed that RL provides relatively fine records in portfolio investment.

Value-Form analysis is the most fundamental in the principles of Marxian political economy and Japan has the most fruitful history of studying value-form in the world. Among them, Kozo Uno’s achievement was influential since his critique of Marx’s value-form analysis gave a clue for capturing the feature of the market in capitalism, but is now losing its momentum due to the lack of an insight into contemporary phenomena such as the fluctuation in asset prices. In order to overcome the deficiency, we shall go back to the text of Capital and try to re-criticise it. In addition, we shall look into the most fierce debate on the Marxian political economy in post-WWII Japan, so-called Uno-Kuruma debate, and conclude that it is not appropriate to leave a quantitative aspect of value-form to focus just on its qualitative aspect. Quantity matters, at least in an economic study, as Uno suggested. Though the value-form has been assumed to be an equality, it can be fundamentally described as a comparative expression of value. As soon as one wants something, s/he compares it with the total value of their assets, wondering whether it is enough for getting what s/he wants. The market is not a field of commodity exchange, but of establishing a quantitative relationship, in which these comparatives turn into equations.