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I read this excerpt from sipser book-

We write “a,b → c” to signify that when the machine is reading an
a from the input, it may replace the symbol b on the top of the stack with a c.
Any of a, b, and c may be ε. If a is ε, the machine may make this transition
without reading any symbol from the input. If b is ε, the machine may make
this transition without reading and popping any symbol from the stack. If c
is ε, then machine does not write any symbol on the stack when going along this
transition.

 

My doubt is, is it possible to move in a PDA without using any stack symbol as written here that top of stack might be epsilon if we don't want to consume it.

If someone can clear my doubt. Thanks

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