Futurama is Awesome

Saturday, January 5, 2013 

I learned two things about Futurama recently which added to my already deep appreciation for the show. The first is that the theme song came from a very cool song by Pierre Henry called Psyche Rock from 1967, which is on youtube. It was remixed by Fatboy Slim in an appealing way.

But what was most interesting recently was to see episode 10 of season 6, the Prisoner of Benda, a spoof of the Prisoner of Zelda but including what may be the first tv-episode publication of the proof of a relatively complex mathematical theorem in group theory as a core plot element.

Prisoner_of_Benda_Theorem_on_Chalkboard.png

The problem in the plot is that the Professor’s mind swapping machine creates an immune response which prevents swapping back in one step. So how do you get everyone back to into their original bodies? Well, as Sweet Clyde says, it takes at most two extra players [who haven’t swapped yet]. As the entire cast, including the robo-bucket, have swapped bodies, the situation is pretty complex, but fortunately one of the show’s writers, Ken Keeler, has a PhD in applied mathematics from Harvard and found a proof, which is actually shown in the show (above), and then worked in a fast montage that restores everyone.

In the following table, the heading shows the character name of the body, row 0 shows the occupant of that body by the end of the plot’s permutations and before the globetrotters start the transformations. Rows 1-7 show the steps to restore everyone to their original bodies.  Each transformation was animated as a pair using the two “extra players” except the last rotation to restore Sweet Clyde and the Bucket.

Posted at 16:34:18 GMT-0700

Category: filmsPositivereviewstechnology

cyrus-sasl-saslauthd-2.1.26 auth_krb5.c compile error

Saturday, January 5, 2013 

Upgrading cyrus-sasl-saslauthd-2.1.25 to the current cyrus-sasl-saslauthd-2.1.26, I started to get auth_krb5.c compile errors that were terminating the compile like:

<command-line>: warning: this is the location of the previous definition
mv -f .deps/auth_getpwent.Tpo .deps/auth_getpwent.Po
cc -DHAVE_CONFIG_H
-DSASLAUTHD_CONF_FILE_DEFAULT=\"/usr/local/etc/saslauthd.conf\" -I. -I.
-I.. -I. -I./include -I./include -I./../include   -I/usr/local/include
-DKRB5_HEIMDAL -I/usr/local/include  -O3 -pipe -march=native
-DLDAP_DEPRECATED -fno-strict-aliasing -MT auth_krb5.o -MD -MP -MF
.deps/auth_krb5.Tpo -c -o auth_krb5.o auth_krb5.c
In file included from mechanisms.h:35,
                 from auth_krb5.c:51:
saslauthd.h:190:1: warning: "KRB5_HEIMDAL" redefined
<command-line>: warning: this is the location of the previous definition
auth_krb5.c: In function 'auth_krb5_init':
auth_krb5.c:105: warning: assignment discards qualifiers from pointer
target type
auth_krb5.c:106: warning: assignment discards qualifiers from pointer
target type
auth_krb5.c: In function 'auth_krb5':
auth_krb5.c:184: error: 'krb5_verify_opt' undeclared (first use in this
function)
auth_krb5.c:184: error: (Each undeclared identifier is reported only once
auth_krb5.c:184: error: for each function it appears in.)
auth_krb5.c:184: error: expected ';' before 'opt'
auth_krb5.c:233: error: 'opt' undeclared (first use in this function)
*** Error code 1

Stop in
/usr/ports/security/cyrus-sasl2-saslauthd/work/cyrus-sasl-2.1.26/saslauthd.
*** Error code 1

Stop in
/usr/ports/security/cyrus-sasl2-saslauthd/work/cyrus-sasl-2.1.26/saslauthd.
*** Error code 1

Stop in /usr/ports/security/cyrus-sasl2-saslauthd.

with some expert advice from the port maintainer, Hajimu UMEMOTO (what is not to love about BSD and open source?  Something goes wrong, the guy who knows everything about it tells you how to fix it right away).   He correctly ascertained that I had security/krb5 installed, a dependency of  openssh-portable.  Kerberos, HEIMDAL and GSSAPI occasionally have interactions, but his advice was to make with the directive KRB5_HOME=/usr/local. I put this into /etc/make.conf to make it permanent, deinstall/reinstalled security/krb5 and then cyrus-sasl-2.1.26 compiled perfectly.

Thanks Mr Umemoto!

Posted at 13:41:23 GMT-0700

Category: FreeBSDtechnology