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23cc023f5b
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@@ -230,7 +230,7 @@ The \textit{tensor product} of two vectors is defined as follows:
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That is, we take our first vector, multiply the second
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vector by each of its components, and stack the result.
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You could think of this as a generalization of scalar
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mulitiplication, where scalar mulitiplication is a
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multiplication, where scalar multiplication is a
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tensor product with a vector in $\mathbb{R}^1$:
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\begin{equation*}
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a
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@@ -81,5 +81,6 @@
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\input{parts/00 intro}
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\input{parts/01 tmam}
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\input{parts/02 kestrel}
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\input{parts/03 bonus}
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\end{document}
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@@ -23,7 +23,7 @@ Complete his proof.
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\lineno{} let A \cmnt{Let A be any any bird.}
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\lineno{} let Cx = A(Mx) \cmnt{Define C as the composition of A and M}
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\lineno{} CC = A(MC)
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\lineno{} = A(CC) \qed{}
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\lineno{} = A(CC)
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\end{alltt}
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\end{solution}
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@@ -46,7 +46,7 @@ Show that the laws of the forest guarantee that at least one bird is egocentric.
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\lineno{}
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\lineno{} ME = E \cmnt{By definition of fondness}
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\lineno{} ME = EE \cmnt{By definition of M}
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\lineno{} \thus{} EE = E \qed{}
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\lineno{} \thus{} EE = E
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\end{alltt}
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\end{solution}
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@@ -99,7 +99,7 @@ Show that if $C$ is agreeable, $A$ is agreeable.
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\lineno{} let y so that Cy = Ey \cmnt{Such a y must exist because C is agreeable}
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\lineno{}
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\lineno{} A(By) = Ey
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\lineno{} = D(By) \qed{}
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\lineno{} = D(By)
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\end{alltt}
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\end{solution}
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@@ -129,6 +129,20 @@ Given three arbitrary birds $A$, $B$, and $C$, show that there exists a bird $D$
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We say two birds $A$ and $B$ are \textit{compatible} if there are birds $x$ and $y$ so that $Ax = y$ and $By = x$. \\
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Note that $x$ and $y$ may be the same bird. \\
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\problem{}
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Show that any bird that is fond of at least one bird is compatible with itself.
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\begin{solution}
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\begin{alltt}
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\lineno{} let A
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\lineno{} let x so that Ax = x \cmnt{A is fond of at least one other bird}
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\lineno{} Ax = x
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\end{alltt}
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\end{solution}
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\vfill
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\problem{}
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Show that any two birds in this forest are compatible. \\
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\begin{alltt}
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@@ -144,7 +158,6 @@ Show that any two birds in this forest are compatible. \\
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\begin{solution}
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\begin{alltt}
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\lineno{} let A, B
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\lineno{}
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\lineno{} let Cx = A(Bx) \cmnt{Composition}
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\lineno{} let y = Cy \cmnt{Let C be fond of y}
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\lineno{}
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@@ -152,24 +165,9 @@ Show that any two birds in this forest are compatible. \\
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\lineno{} = A(By)
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\lineno{}
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\lineno{} let x = By \cmnt{Rename By to x}
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\lineno{} Ax = y \qed{}
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\lineno{} Ax = y
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\end{alltt}
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\end{solution}
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\vfill
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\problem{}
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Show that any bird that is fond of at least one bird is compatible with itself.
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\begin{solution}
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\begin{alltt}
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\lineno{} let A
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\lineno{} let x so that Ax = x \cmnt{A is fond of at least one other bird}
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\lineno{} Ax = x \qed{}
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\end{alltt}
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That's it.
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\end{solution}
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\vfill
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\pagebreak
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@@ -18,7 +18,7 @@ Say $A$ is fixated on $B$. Is $A$ fond of $B$?
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\begin{alltt}
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\lineno{} let A
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\lineno{} let B so that Ax = B
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\lineno{} \thus{} AB = B \qed{}
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\lineno{} \thus{} AB = B
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\end{alltt}
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\end{solution}
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\vfill
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@@ -39,7 +39,7 @@ Show that an egocentric Kestrel is hopelessly egocentric.
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\begin{alltt}
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\lineno{} KK = K
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\lineno{} \thus{} (KK)y = K \cmnt{By definition of the Kestrel}
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\lineno{} \thus{} Ky = K \qed{} \cmnt{By 01}
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\lineno{} \thus{} Ky = K \cmnt{By 01}
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\end{alltt}
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\end{solution}
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@@ -64,7 +64,7 @@ Given the Law of Composition and the Law of the Mockingbird, show that at least
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\begin{alltt}
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\lineno{} let A so that KA = A \cmnt{Any bird is fond of at least one bird}
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\lineno{} (KA)y = y \cmnt{By definition of the kestrel}
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\lineno{} \thus{} Ay = A \qed{} \cmnt{By 01}
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\lineno{} \thus{} Ay = A \cmnt{By 01}
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\end{alltt}
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\end{solution}
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@@ -90,7 +90,7 @@ Show that $Kx = Ky \implies x = y$.
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\lineno{} (Kx)z = x
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\lineno{} (Ky)z = y
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\lineno{}
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\lineno{} \thus{} x = (Kx)z = (Ky)z = y \qed{}
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\lineno{} \thus{} x = (Kx)z = (Ky)z = y
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\end{alltt}
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\end{solution}
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@@ -128,7 +128,7 @@ An egocentric Kestrel must be extremely lonely. Why is this?
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\lineno{} Ky = K
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\lineno{} Kx = Ky
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\lineno{} x = y for all x, y \cmnt{By \ref{leftcancel}}
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\lineno{} x = y = K \qed{} \cmnt{By 10, and since K exists}
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\lineno{} x = y = K \cmnt{By 10, and since K exists}
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\end{alltt}
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\end{solution}
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102
src/Advanced/Mock a Mockingbird/parts/03 bonus.tex
Normal file
102
src/Advanced/Mock a Mockingbird/parts/03 bonus.tex
Normal file
@@ -0,0 +1,102 @@
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\section{Bonus Problems}
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\definition{}
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The identity bird has sometimes been maligned, owing to
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the fact that whatever bird x you call to $I$, all $I$ does is to echo
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$x$ back to you.
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\vspace{2mm}
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Superficially, the bird $I$ appears to have no intelligence or imagination; all it can do is repeat what it hears.
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For this reason, in the past, thoughtless students of ornithology
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referred to it as the idiot bird. However, a more profound or-
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nithologist once studied the situation in great depth and dis-
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covered that the identity bird is in fact highly intelligent! The
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real reason for its apparently unimaginative behavior is that it
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has an unusually large heart and hence is fond of every bird!
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When you call $x$ to $I$, the reason it responds by calling back $x$
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is not that it can't think of anything else; it's just that it wants
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you to know that it is fond of $x$!
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\vspace{2mm}
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Since an identity bird is fond of every bird, then it is also
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fond of itself, so every identity bird is egocentric. However,
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its egocentricity doesn't mean that it is any more fond of itself
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than of any other bird!.
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\problem{}
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The laws of the forest no longer apply.
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Suppose we are told that the forest contains an identity bird
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$I$ and that $I$ is agreeable. \
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Does it follow that every bird must be fond of at least one bird?
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\vfill
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\problem{}
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Suppose we are told that there is an identity bird $I$ and that
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every bird is fond of at least one bird. \
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Does it necessarily follow that $I$ is agreeable?
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\vfill
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\pagebreak
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\problem{}
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Suppose we are told that there is an identity bird $I$, but we are
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not told whether $I$ is agreeable or not.
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However, we are told that every pair of birds is compatible. \
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Which of the following conclusiens can be validly drawn?
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\begin{itemize}
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\item Every bird is fond of at least one bird
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\item $I$ is agreeable.
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\end{itemize}
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\vfill
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\problem{}
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The identity bird $I$, though egocentric, is in general not hope-
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lessly egocentric. Indeed, if there were a hopelessly egocentric
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identity bird, the situation would be quite sad. Why?
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\vfill
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\definition{}
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A bird $L$ is called a lark if the following
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holds for any birds $x$ and $y$:
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\[
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(Lx)y = x(yy)
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\]
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\problem{}
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Prove that if the forest contains a lark $L$ and an identity bird
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$I$, then it must also contain a mockingbird $M$.
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\vfill
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\pagebreak
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\problem{}
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Why is a hopelessly egocentric lark unusually attractive?
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\vfill
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\problem{}
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Assuming that no bird can be both a lark and a kestrel---as
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any ornithologist knows!---prove that it is impossible for a
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lark to be fond of a kestrel.
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\vfill
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\problem{}
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It might happen, however, that a kestrel is fond of a lark. \par
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Show that in this case, \textit{every} bird is fond of the lark.
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\vfill
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@@ -251,7 +251,7 @@ What is it, and what is its color? \par
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\textbf{Part 4:}
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The promoted black bishop on H2 must have been promoted on G1. The pawn which was promoted must have come from G7,
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since neither of the pawns from F6 or H6 could make a capture to get to the G-file (all six missing white pieces have been accouted for).
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since neither of the pawns from F6 or H6 could make a capture to get to the G-file (all six missing white pieces have been accounted for).
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The Pawn from E7 has promoted to the bishop on A2.
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What happened was this: the white pawn from G2 made its capture on H3 while the pawn on G3 was still on H2. This allowed the black pawn
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@@ -331,7 +331,7 @@
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representing all four cubes. \\
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\begin{center} \begin{small}
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\begin{tikzpicture} \label{pic:II_comfiguration}
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\begin{tikzpicture} \label{pic:II_configuration}
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\filldraw [blue] (0,5) -- (1,5) -- (1,6) --
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(0,6) -- (0,5);
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\draw [line width = 1.5pt] (0,5) --
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