RACSO
R
DFA
CFG
Operations:
Reg
,
CF
PDA
Reductions:
K
,
WP
,
CFG
,
NP
,
SAT
ANTLR:
lex
,
syn
Exams
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Exercise 1
›
:
Context-free description for
{
w
∈
{
a
,
b
}
∗
∣
∣
w
∣
a
=
∣
w
∣
b
∧
∣
w
∣
a
b
b
a
>
0
}
\{ w \in \{a,b\}^* \mid |w|_a=|w|_b\;\wedge\;|w|_{abba}>0 \}
{
w
∈
{
a
,
b
}
∗
∣
∣
w
∣
a
=
∣
w
∣
b
∧
∣
w
∣
abba
>
0
}
Give a context-free description for the set of words over
{
a
,
b
}
\{a,b\}
{
a
,
b
}
with the same number of
a
a
a
’s as number of
b
b
b
’s, and with at least one occurrence of
a
b
b
a
abba
abba
.
Authors:
Guillem Godoy /
Documentation:
main { // Write here your context-free description... }
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