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First Generalizations

Replacing $ D(P\vert\vert Q)$ by $ {\ensuremath{\boldsymbol{\mathscr{D}}}}^s_r(P\vert\vert Q)$ in the expressions (2.6) and (2.4),we get
$\displaystyle ^1{\ensuremath{\boldsymbol{\mathscr{I}}}}^s_r(P\vert\vert Q)= {1\......uremath{\boldsymbol{\mathscr{D}}}}^s_r\big( Q\vert\vert{P+Q\over2}\big)\Bigg],$
    (4.6)
and
$\displaystyle ^1{\ensuremath{\boldsymbol{\mathscr{J}}}}^s_r(P\vert\vert Q)= {\e......^s_r(P\vert\vert Q)+{\ensuremath{\boldsymbol{\mathscr{D}}}}^s_r(Q\vert\vert P),$
    (4.7)
respectively.

The unified $ (r,s)-$divergence measures according to the expression (4.6) is given by

$\displaystyle ^1{\ensuremath{\boldsymbol{\mathscr{I}}}}^s_r(P\vert\vert Q)=\lef......), & r\neq 1,\ \ s=1 \\  I(P\vert\vert Q), & r=1,\ \s=1\end{array}\right.$
where

$ \displaystyle^1I^s_r(P\vert\vert Q)=(1-2^{1-s})^{-1}\Bigg\{ \Big[ \sum_{i=1}^n{p^r_i\Big( {p_i+q_i\over 2}\Big) ^{1-r}}\Big]^{s-1\over r-1}+$

$\displaystyle \Big[\sum_{i=1}^n{q^r_i \Big( {p_i+q_i\over 2}\Big)^{1-r}}\Big]^{s-1\over r-1} -2\Bigg\},\ r\neq 1,\ s\neq 1$
$ \displaystyle^1I^s_1(P\vert\vert Q)=(1-2^{1-s})^{-1}\Big\{ \exp_2\Big[ (s-1)\sum_{i=1}^n{p_i\,\log \Big( {2p_i\over p_i+q_i}\Big)}\Big]+$
$\displaystyle \exp_2\Big[ (s-1)\sum_{i=1}^n{q_i\,\log \Big( {2q_i\overp_i+q_i}\Big)} \Big]-2 \Big\},\ s\neq 1$
and
$\displaystyle ^1I^1_r(P\vert\vert Q)=\big[ 2(r-1)\big]^{-1}\log\Big\{ \Big[\s......\sum_{i=1}^n{q^r_i \Big( {p_i+q_i\over 2}\Big) ^{1-r}}\Big]\Big\},\ r\neq 1$

The unified $ (r,s)-$divergence measures according to the expression (4.7) is given by

$\displaystyle ^1{\ensuremath{\boldsymbol{\mathscr{J}}}}^s_r(P\vert\vert Q)=\lef......), & r\neq 1,\ \ s=1 \\  J(P\vert\vert Q), & r=1,\ \s=1\end{array}\right.$
where

$ \displaystyle^1J^s_r(P\vert\vert Q)=(1-2^{1-s})^{-1}\Bigg\{\Big( \sum_{i=1}^n{p^r_iq^{1-r}_i}\Big)^{s-1\over r-1}+$

$\displaystyle \Big( \sum_{i=1}^n{p^r_iq^{1-r}_i}\Big)^{s-1\over r-1} -2\Bigg\},\ r\neq 1,\ s\neq 1$

$ \displaystyle^1J^s_1(P\vert\vert Q)=(1-2^{1-s})^{-1}\Big\{\exp_2 \Big( (s-1)\sum_{i=1}^n{p_i \log{p_i\over q_i}}\Big)+$

$\displaystyle \exp_2\Big((s-1)\sum_{i=1}^n{q_i\log{q_i\over p_i}}\Big) -2\Big\},\ s\neq 1$
and

$ \displaystyle ^1J^1_r(P\vert\vert Q)=(r-1)^{-1}\log\Big\{\Big( \sum_{i=1}^n{p^r_i q^{1-r}_i}\Big) \Big(\sum_{i=1}^n{q^r_ip^{1-r}_i}\Big)\Big\},\ r\neq 1$

In particular, when $ r=s$, we have

$ ^1I^s_s(P\vert\vert Q) = I^s_s(P\vert\vert Q)$

$\displaystyle = (1-2^{1-s})^{-1} \Big\{\sum_{i=1}^n{\Big({p^s_i+q^s_i\over2}\Big)\Big({p_i+q_i\over 2}\Big)^{1-s}-1}\Big\},\ s\neq 1,\ s>0$
    (4.8)
and

$ ^1J^s_s(P\vert\vert Q)=J^s_s(P\vert\vert Q)$

$\displaystyle = (1-2^{1-s})^{-1} \Big\{\sum_{i=1}^n{\big(p^s_iq^{1-s}_i+p^{1-s}_iq^s_i\big)}-2\Big\},\ s\neq 1,\ s>0$
    (4.9)

The expressions appearing in (4.8) and (4.9) shall be used to give an alternative way for generalizing unified $ (r,s)-$divergence measures.


21-06-2001
Inder Jeet Taneja
Departamento de Matemática - UFSC
88.040-900 Florianópolis, SC - Brazil