Problem 1.5. Sho w that the fancy pretzel represented in Figure 1.4 (a) can
be deformed int o the ordinary pretzel with two holes (Figure 1.4 (b)).
(a) (b )
We present mos t o f the solutions to the problems in this book by means
of pictures, which, as a rule, are self-explanatory. W e sometimes indicate by
arrows on the pictures the direction of motion or of deformation .
1.1. Se e Figure 1.5. We shall return to this deformation i n §4.