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Comments on Lecture 8 "Invisible Chicken"

Comment 1. Why doesn't the object fell down?


The rectangular cylinder looks like standing stably on an edge. Actually it is not a rectangular cylinder, but the lower half is the horizontal picture drawn on both sides. Hence, it does not fell down.

Comment 2. Why does the hen disappear completely?

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If the hen stands vertically, it cannot be hidden in the mirror. However, we place the hen in a slanted posture, and hence can hide it behind the top plate completely. To make the hen appear vertical, we compress the picture of the hen in the vertical direction.

Comment 3. Unfolded surface of the "Invisible Chicken"


The unfolded surface of the "Invisible Chicken" for paper crafting is placed here. We can print it on a sheet of A4 size paper, and construct the object by cutting and gluing.

For those who want to use the construction kit


Set of Strange Objects That Change in a Mirror (in Japanese)@(Authored by K. Sugihara, and published by Tokyo Shoseki Publisher)
This set includes the diagrams of the unfolded surfaces of three "Partly Invisible Objects,"


Illusion Trick Kit (in Japanese)@(Authored by K. Sugihara, and published by Gentosha Publisher)
It includes five objects, one of which is a "Partly Invisible Object."

Reference on the partly invisible objects

K. Sugihara: A New Type of Impossible Objects That Become Partly Invisible in a Mirror. Japan Journal of Indsutrial and Applied Mathematics, vol. 33 (2016), pp. 525-535.
(This paper won the Best Paper Prize of the Japan Society of Industiral and Applied Mathematics in 2017)