2 Commits

Author SHA1 Message Date
23cc023f5b Mockingbird edits
All checks were successful
CI / Typst formatting (pull_request) Successful in 7s
CI / Typos (pull_request) Successful in 10s
CI / Build (pull_request) Successful in 10m16s
2026-02-15 10:39:59 -08:00
b25ab0d5e0 fix typos
All checks were successful
CI / Typst formatting (pull_request) Successful in 5s
CI / Typos (pull_request) Successful in 11s
CI / Build (pull_request) Successful in 5m18s
2026-02-15 10:36:50 -08:00
7 changed files with 129 additions and 28 deletions

View File

@@ -230,7 +230,7 @@ The \textit{tensor product} of two vectors is defined as follows:
That is, we take our first vector, multiply the second That is, we take our first vector, multiply the second
vector by each of its components, and stack the result. vector by each of its components, and stack the result.
You could think of this as a generalization of scalar You could think of this as a generalization of scalar
mulitiplication, where scalar mulitiplication is a multiplication, where scalar multiplication is a
tensor product with a vector in $\mathbb{R}^1$: tensor product with a vector in $\mathbb{R}^1$:
\begin{equation*} \begin{equation*}
a a

View File

@@ -81,5 +81,6 @@
\input{parts/00 intro} \input{parts/00 intro}
\input{parts/01 tmam} \input{parts/01 tmam}
\input{parts/02 kestrel} \input{parts/02 kestrel}
\input{parts/03 bonus}
\end{document} \end{document}

View File

@@ -23,7 +23,7 @@ Complete his proof.
\lineno{} let A \cmnt{Let A be any any bird.} \lineno{} let A \cmnt{Let A be any any bird.}
\lineno{} let Cx = A(Mx) \cmnt{Define C as the composition of A and M} \lineno{} let Cx = A(Mx) \cmnt{Define C as the composition of A and M}
\lineno{} CC = A(MC) \lineno{} CC = A(MC)
\lineno{} = A(CC) \qed{} \lineno{} = A(CC)
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -46,7 +46,7 @@ Show that the laws of the forest guarantee that at least one bird is egocentric.
\lineno{} \lineno{}
\lineno{} ME = E \cmnt{By definition of fondness} \lineno{} ME = E \cmnt{By definition of fondness}
\lineno{} ME = EE \cmnt{By definition of M} \lineno{} ME = EE \cmnt{By definition of M}
\lineno{} \thus{} EE = E \qed{} \lineno{} \thus{} EE = E
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -99,7 +99,7 @@ Show that if $C$ is agreeable, $A$ is agreeable.
\lineno{} let y so that Cy = Ey \cmnt{Such a y must exist because C is agreeable} \lineno{} let y so that Cy = Ey \cmnt{Such a y must exist because C is agreeable}
\lineno{} \lineno{}
\lineno{} A(By) = Ey \lineno{} A(By) = Ey
\lineno{} = D(By) \qed{} \lineno{} = D(By)
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -129,6 +129,20 @@ Given three arbitrary birds $A$, $B$, and $C$, show that there exists a bird $D$
We say two birds $A$ and $B$ are \textit{compatible} if there are birds $x$ and $y$ so that $Ax = y$ and $By = x$. \\ We say two birds $A$ and $B$ are \textit{compatible} if there are birds $x$ and $y$ so that $Ax = y$ and $By = x$. \\
Note that $x$ and $y$ may be the same bird. \\ Note that $x$ and $y$ may be the same bird. \\
\problem{}
Show that any bird that is fond of at least one bird is compatible with itself.
\begin{solution}
\begin{alltt}
\lineno{} let A
\lineno{} let x so that Ax = x \cmnt{A is fond of at least one other bird}
\lineno{} Ax = x
\end{alltt}
\end{solution}
\vfill
\problem{} \problem{}
Show that any two birds in this forest are compatible. \\ Show that any two birds in this forest are compatible. \\
\begin{alltt} \begin{alltt}
@@ -144,7 +158,6 @@ Show that any two birds in this forest are compatible. \\
\begin{solution} \begin{solution}
\begin{alltt} \begin{alltt}
\lineno{} let A, B \lineno{} let A, B
\lineno{}
\lineno{} let Cx = A(Bx) \cmnt{Composition} \lineno{} let Cx = A(Bx) \cmnt{Composition}
\lineno{} let y = Cy \cmnt{Let C be fond of y} \lineno{} let y = Cy \cmnt{Let C be fond of y}
\lineno{} \lineno{}
@@ -152,24 +165,9 @@ Show that any two birds in this forest are compatible. \\
\lineno{} = A(By) \lineno{} = A(By)
\lineno{} \lineno{}
\lineno{} let x = By \cmnt{Rename By to x} \lineno{} let x = By \cmnt{Rename By to x}
\lineno{} Ax = y \qed{} \lineno{} Ax = y
\end{alltt} \end{alltt}
\end{solution} \end{solution}
\vfill
\problem{}
Show that any bird that is fond of at least one bird is compatible with itself.
\begin{solution}
\begin{alltt}
\lineno{} let A
\lineno{} let x so that Ax = x \cmnt{A is fond of at least one other bird}
\lineno{} Ax = x \qed{}
\end{alltt}
That's it.
\end{solution}
\vfill \vfill
\pagebreak \pagebreak

View File

@@ -18,7 +18,7 @@ Say $A$ is fixated on $B$. Is $A$ fond of $B$?
\begin{alltt} \begin{alltt}
\lineno{} let A \lineno{} let A
\lineno{} let B so that Ax = B \lineno{} let B so that Ax = B
\lineno{} \thus{} AB = B \qed{} \lineno{} \thus{} AB = B
\end{alltt} \end{alltt}
\end{solution} \end{solution}
\vfill \vfill
@@ -39,7 +39,7 @@ Show that an egocentric Kestrel is hopelessly egocentric.
\begin{alltt} \begin{alltt}
\lineno{} KK = K \lineno{} KK = K
\lineno{} \thus{} (KK)y = K \cmnt{By definition of the Kestrel} \lineno{} \thus{} (KK)y = K \cmnt{By definition of the Kestrel}
\lineno{} \thus{} Ky = K \qed{} \cmnt{By 01} \lineno{} \thus{} Ky = K \cmnt{By 01}
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -64,7 +64,7 @@ Given the Law of Composition and the Law of the Mockingbird, show that at least
\begin{alltt} \begin{alltt}
\lineno{} let A so that KA = A \cmnt{Any bird is fond of at least one bird} \lineno{} let A so that KA = A \cmnt{Any bird is fond of at least one bird}
\lineno{} (KA)y = y \cmnt{By definition of the kestrel} \lineno{} (KA)y = y \cmnt{By definition of the kestrel}
\lineno{} \thus{} Ay = A \qed{} \cmnt{By 01} \lineno{} \thus{} Ay = A \cmnt{By 01}
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -90,7 +90,7 @@ Show that $Kx = Ky \implies x = y$.
\lineno{} (Kx)z = x \lineno{} (Kx)z = x
\lineno{} (Ky)z = y \lineno{} (Ky)z = y
\lineno{} \lineno{}
\lineno{} \thus{} x = (Kx)z = (Ky)z = y \qed{} \lineno{} \thus{} x = (Kx)z = (Ky)z = y
\end{alltt} \end{alltt}
\end{solution} \end{solution}
@@ -128,7 +128,7 @@ An egocentric Kestrel must be extremely lonely. Why is this?
\lineno{} Ky = K \lineno{} Ky = K
\lineno{} Kx = Ky \lineno{} Kx = Ky
\lineno{} x = y for all x, y \cmnt{By \ref{leftcancel}} \lineno{} x = y for all x, y \cmnt{By \ref{leftcancel}}
\lineno{} x = y = K \qed{} \cmnt{By 10, and since K exists} \lineno{} x = y = K \cmnt{By 10, and since K exists}
\end{alltt} \end{alltt}
\end{solution} \end{solution}

View File

@@ -0,0 +1,102 @@
\section{Bonus Problems}
\definition{}
The identity bird has sometimes been maligned, owing to
the fact that whatever bird x you call to $I$, all $I$ does is to echo
$x$ back to you.
\vspace{2mm}
Superficially, the bird $I$ appears to have no intelligence or imagination; all it can do is repeat what it hears.
For this reason, in the past, thoughtless students of ornithology
referred to it as the idiot bird. However, a more profound or-
nithologist once studied the situation in great depth and dis-
covered that the identity bird is in fact highly intelligent! The
real reason for its apparently unimaginative behavior is that it
has an unusually large heart and hence is fond of every bird!
When you call $x$ to $I$, the reason it responds by calling back $x$
is not that it can't think of anything else; it's just that it wants
you to know that it is fond of $x$!
\vspace{2mm}
Since an identity bird is fond of every bird, then it is also
fond of itself, so every identity bird is egocentric. However,
its egocentricity doesn't mean that it is any more fond of itself
than of any other bird!.
\problem{}
The laws of the forest no longer apply.
Suppose we are told that the forest contains an identity bird
$I$ and that $I$ is agreeable. \
Does it follow that every bird must be fond of at least one bird?
\vfill
\problem{}
Suppose we are told that there is an identity bird $I$ and that
every bird is fond of at least one bird. \
Does it necessarily follow that $I$ is agreeable?
\vfill
\pagebreak
\problem{}
Suppose we are told that there is an identity bird $I$, but we are
not told whether $I$ is agreeable or not.
However, we are told that every pair of birds is compatible. \
Which of the following conclusiens can be validly drawn?
\begin{itemize}
\item Every bird is fond of at least one bird
\item $I$ is agreeable.
\end{itemize}
\vfill
\problem{}
The identity bird $I$, though egocentric, is in general not hope-
lessly egocentric. Indeed, if there were a hopelessly egocentric
identity bird, the situation would be quite sad. Why?
\vfill
\definition{}
A bird $L$ is called a lark if the following
holds for any birds $x$ and $y$:
\[
(Lx)y = x(yy)
\]
\problem{}
Prove that if the forest contains a lark $L$ and an identity bird
$I$, then it must also contain a mockingbird $M$.
\vfill
\pagebreak
\problem{}
Why is a hopelessly egocentric lark unusually attractive?
\vfill
\problem{}
Assuming that no bird can be both a lark and a kestrel---as
any ornithologist knows!---prove that it is impossible for a
lark to be fond of a kestrel.
\vfill
\problem{}
It might happen, however, that a kestrel is fond of a lark. \par
Show that in this case, \textit{every} bird is fond of the lark.
\vfill

View File

@@ -251,7 +251,7 @@ What is it, and what is its color? \par
\textbf{Part 4:} \textbf{Part 4:}
The promoted black bishop on H2 must have been promoted on G1. The pawn which was promoted must have come from G7, The promoted black bishop on H2 must have been promoted on G1. The pawn which was promoted must have come from G7,
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). 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).
The Pawn from E7 has promoted to the bishop on A2. The Pawn from E7 has promoted to the bishop on A2.
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 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

View File

@@ -331,7 +331,7 @@
representing all four cubes. \\ representing all four cubes. \\
\begin{center} \begin{small} \begin{center} \begin{small}
\begin{tikzpicture} \label{pic:II_comfiguration} \begin{tikzpicture} \label{pic:II_configuration}
\filldraw [blue] (0,5) -- (1,5) -- (1,6) -- \filldraw [blue] (0,5) -- (1,5) -- (1,6) --
(0,6) -- (0,5); (0,6) -- (0,5);
\draw [line width = 1.5pt] (0,5) -- \draw [line width = 1.5pt] (0,5) --