Chapter 2 review. Are the following statements true or false? Explain why or why not.
a) "Elementary, my dear Watson,"
alludes to Holmes' analytical approach to problem solving.
True. a mysterious solution proves elementary when Holmes explains the analytical
steps he has taken.
b) Hacking is a common but not
a recommended problem solving strategy for novices.
True. Blind hacking is a slow and cumbersome way to program and produces awkward
programs.
c) Analogical reasoning involves
breaking a problem down into smaller problems.
False. That's analytical reasoning--analogical reasoning exploits
similarities.
d) A recipe is analogous to a well-defined
solution to a problem.
True. It tells precisely how to achieve the desired goal (the dish to be prepared).
e) Sentences and programs are both
essentially sequential structures.
False. Although they have a sequential appearance, they both have underlying
non-sequential structures.
f) Famous detectives and expert
hackers ignore considering the givens and goals of a problem.
False. Understanding the givens and goals is essential for good problem solving.
g) Turing kept the resources of
Turing machines in his head.
False. The resources of a Turing machine were made explicit--move, read, write,
etc.
h) The resources of Knobby's World
are its walls and characters.
False. These are the givens--the
resources are the moves Knobby can make.
i) The givens of Knobby's World
are defined in its situation file.
True. The situation file shows the givens--the walls and characters.
j) Real world problems usually
start out well-defined.
False. Making the definition clear is a crucial first step in problem solving.
k) A "blinder" effect can cause
us to miss important givens, goals or resources of a problem.
True. The "blinder" effect keeps us focused on the familiar, thus overlooking
important novel features of a problem.
l) Preliminary analysis begins
the implementation of a program.
True. After perhaps a few earlier orientation questions, preliminary analysis
is a crucial early step in problem solving.
m) In the fox-goose-corn problem,
the location of the boat is a variant, accounted for in our notation.
False. Though the boat moves from shore to shore, it's always on the same side
of the river as you (the rower), thus it requires no additional notation.
n) A blind hacking approach can
get "blind-sided" by a combinatorial explosion.
True. Although the fox-corn-goose program is a relatively simple case, it's
easy to find much more complicated ones.
o) Informed hacking relies on knowledge
of a problem domain to get through a problem space.
True. Informed hackers know the characteristics of the problem space well--that's
why it's called "informed hacking."
p) Interacting sub-goals is something
that only happens in toy, "blocks world" problems.
False. Think of scheduling classes, for instance.
q) Decomposition is an excellent
way to tackle problems about which one has little knowledge.
True. Thinking about the parts of a problem is an easy way to understand it
better.
r) Analogical problem solving is
just copying an old solution, as is, into a new problem.
False. There are often important differences to take into account.
s) Object-oriented programming
combines analogical and bottom-up problem solving strategies.
True. Object-oriented approaches emphasize reusing standard task "packages"
in similar situations.
t) The first task of object-oriented
problem solving is decomposing down to primitive actions.
False . Object-oriented programming is a form of analogical problem solving,
seeking to reuse or extend existing classes or components.
v) A Knobby program must have one
main instruction, appearing at the top of the program.
False. A Knobby program must have one (and only one) main instruction,
and the main instruction must appear at the bottom
of the program, after defining any other instructions.
x) Knobby keeps some handy, reusable
instructions for composition of programs in his head.
False. His head can only store up to two characters, in its "blackboards". But
you can load reusable instructions in Knobby's World programs.