Translations
the Translate class indicates that a code block will contain translation
exercises that require symbolizing natural language sentences.
Propositional Logic
You can create propositional logic translation problems by also adding the
class Prop, like so:
~~~{.Translate .Prop}
3.1 P/\Q : People want to know what's going on and questions are unavoidable
~~~
The number 3.1 indicates the exercise number, and the colon separates the solution from the text that will be presented for translation. The result of the above is:
To complete it, replace the text to the left of the submit solution button with
your translation, press return to check, and then press "Submit Solution".
Propositional translations are considered correct if they are logically
equivalent to the original answer. So for example, Q/\P will be accepted
above.
First-Order Translation
It is also possible to create first-order translation problems using the class FOL, thus:
~~~{.Translate .FOL}
3.2 AxF(x) : Everything is fine
~~~
with the result:
These are completed as above. Equivalence of first-order sentences is
undecidable, so we can't check it, but we can catch most cases of "equivalent"
translations by using some rewriting rules.1 So, for example ~Ex~F(x) will
be accepted above.
Exact Translations
Using the class Exact, you can also create "translations" that don't accept
logically equivalent answers. These may be useful if you wish to, for example,
ask a student what the missing premise in some inference is. So, for example
you might write
~~~{.Translate .Exact}
3.3 P : To make a modus ponens inference with P→Q, you need...
~~~
to generate:
Exact translations use the same syntax as Prop by default, but can be
configured to use a large number of alternative syntaxes (see below)
Systems
The way that formulas are parsed can also be customized. This is done by
setting the system attribute to indicate which formal system you are drawing
your syntax from. So for example,
~~~{.Translate .FOL system="magnusQL"}
3.5 AxBx : Everything is bananas
~~~
will generate:
For first-order translations, the available systems are: firstOrder
montagueQC magnusQL thomasBolducAndZachFOL thomasBolducAndZachFOL2019
LogicBookPD LogicBookPDPlus hausmanPL howardSnyderPL
ichikawaJenkinsQL hardegreePL goldfarbAltND goldfarbNDPlus and
goldfarbAltNDPlus.
For propositional translations, the available systems are: prop montagueSC
LogicBookSD LogicBookSDPlus hausmanSL howardSnyderSL
ichikawaJenkinsSL hausmanSL magnusSL magnusSLPlus
thomasBolducAndZachTFL thomasBolducAndZachTFL2019 tomassiPL and
hardegreeSL.
For exact translations, the available systems are all of the above, together
with modal logic systems .HardegreeSL .HardegreePL .HardegreeWTL,
.HardegreeL .HardegreeK .HardegreeT .HardegreeB .HardegreeD
.Hardegree4 .Hardegree5, second order systems .SecondOrder
.PolySecondOrder, and set theory systems ElementaryST and
SeparativeST
Advanced usage
Multiple Solutions
If you wish to allow students to find one translation of a sentence that admits several formalizations, you can use a comma-separated list of admissible solutions. So,
~~~{.Translate .FOL}
3.4 (P /\ Q) \/ R, P/\(Q\/R) : Jack jumped the fence and was caught by the watchman or got away.
~~~
generates
Options and Attributes
In addition to allowing for custom point values with points=VALUE, and
turning off submission with submission="none", translations also have the
following options
| Name | Effect |
|---|---|
nocheck |
Disables checking solutions |
exam |
Allows for submission of work which is incomplete or incorrect |
checksyntax |
When exam is active, blocks submission of syntactically incorrect work |
These can be included in the space separated list supplied to the options
attribute.
Translation tests
Finally, you can impose one or more extra tests on a translation. This is done
by setting the tests attribute to indicate which tests you wish to require
the translation to pass. The available tests for propositional translations are
| Name | Effect |
|---|---|
CNF |
Requires conjunctive normal form |
DNF |
Requires disjunctive normal form |
maxCon:N |
Requires that the translation contain N or fewer connectives |
maxNot:N |
Requires that the translation contain N or fewer negations |
maxAnd:N |
Requires that the translation contain N or fewer conjunctions |
maxIff:N |
Requires that the translation contain N or fewer biconditionals |
maxIf:N |
Requires that the translation contain N or fewer conditionals |
maxOr:N |
Requires that the translation contain N or fewer disjunctions |
maxFalse:N |
Requires that the translation contain N or fewer falsity constants |
maxAtom:N |
Requires that the translation contain N or fewer atomic sentences |
The available tests for first-order translations are all the propositional tests, plus:
| Name | Effect |
|---|---|
PNF |
Requires prenex normal form |
When using multiple tests, their names must be separated by spaces, so for example,
~~~{.Translate .FOL tests="PNF maxNeg:0"}
3.6 ~Ex~F(x) : Nothing is not bananas.
~~~
will generate:
Partial Solutions
It's possible to include a partial solution to a translation problem, by
including the partial solution after a | following the problem. So for
example,
~~~{.Translate .FOL options="nocheck"}
3.7 AxF(x) : Everything is fine
| For all x, x is fine
~~~
Generates
the procedure is roughly as follows:
- using the standard rules of passage, drive quantifiers in as far as possible in both the submitted solution S0, and in the target sentence T0, generating two result sentences S1,T1
- using the standard rules of passage, pull out quantifiers as far as possible, in every possible way, generating a set S2 of sentences from S1, and a set of sentences T2 from T1
- allowing permutation of quantifiers within blocks, look for pairs of sentences (S3,T3) with matching quantifier prefixes. Canonically rename the variables. Check the matricies of the resulting formulas for propositional equivalence.